From 8f016530706bbad2d5dc041a0e3a093cbd637474 Mon Sep 17 00:00:00 2001
From: Mattias-Sehlstedt <60173714+Mattias-Sehlstedt@users.noreply.github.com>
Date: Sun, 14 Dec 2025 23:27:55 +0100
Subject: [PATCH] [Java] [Spring Client] Add an exception provider interface to
 allow for easy exception redefinition

---
 .../codegen/languages/JavaClientCodegen.java  |  2 +
 .../resources/Java/ExceptionProvider.mustache | 68 ++++++++++++++++
 .../libraries/restclient/ApiClient.mustache   | 48 ++++++++---
 .../libraries/webclient/ApiClient.mustache    | 48 ++++++++---
 .../java/restclient/.openapi-generator/FILES  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../java/restclient/.openapi-generator/FILES  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 46 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../.openapi-generator/FILES                  |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 .../java/webclient/.openapi-generator/FILES   |  1 +
 .../org/openapitools/client/ApiClient.java    | 48 ++++++++---
 .../client/ExceptionProvider.java             | 79 +++++++++++++++++++
 70 files changed, 2707 insertions(+), 253 deletions(-)
 create mode 100644 modules/openapi-generator/src/main/resources/Java/ExceptionProvider.mustache
 create mode 100644 samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java
 create mode 100644 samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ExceptionProvider.java

diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
index f779be9ed183..befc33f19e84 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/JavaClientCodegen.java
@@ -720,6 +720,7 @@ public void processOpts() {
             // one by one for each library.
             supportsAdditionalPropertiesWithComposedSchema = true;
         } else if (libWebClient) {
+            supportingFiles.add(new SupportingFile("ExceptionProvider.mustache", invokerFolder, "ExceptionProvider.java"));
             forceSerializationLibrary(SERIALIZATION_LIBRARY_JACKSON);
 
             // Composed schemas can have the 'additionalProperties' keyword, as specified in JSON schema.
@@ -729,6 +730,7 @@ public void processOpts() {
             // one by one for each library.
             supportsAdditionalPropertiesWithComposedSchema = true;
         } else if (libRestClient) {
+            supportingFiles.add(new SupportingFile("ExceptionProvider.mustache", invokerFolder, "ExceptionProvider.java"));
             forceSerializationLibrary(SERIALIZATION_LIBRARY_JACKSON);
             applyJakartaPackage();
 
diff --git a/modules/openapi-generator/src/main/resources/Java/ExceptionProvider.mustache b/modules/openapi-generator/src/main/resources/Java/ExceptionProvider.mustache
new file mode 100644
index 000000000000..81ad9020e2f4
--- /dev/null
+++ b/modules/openapi-generator/src/main/resources/Java/ExceptionProvider.mustache
@@ -0,0 +1,68 @@
+{{>licenseInfo}}
+
+package {{invokerPackage}};
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache
index 61dac36a2540..a30bf9d25b6e 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/restclient/ApiClient.mustache
@@ -149,6 +149,13 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
     {{/useJackson3}}
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -351,6 +358,25 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -372,7 +398,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -387,7 +413,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -401,7 +427,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -415,7 +441,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -429,7 +455,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -443,7 +469,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     {{#hasOAuthMethods}}
@@ -468,7 +494,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return this;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     {{/hasOAuthMethods}}
@@ -524,7 +550,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -592,7 +618,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch ({{#useJackson3}}JacksonException{{/useJackson3}}{{^useJackson3}}JsonProcessingException{{/useJackson3}} e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -601,7 +627,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch ({{#useJackson3}}JacksonException{{/useJackson3}}{{^useJackson3}}JsonProcessingException{{/useJackson3}} e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -935,7 +961,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache
index e1df6981f724..0231dd08cf27 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/webclient/ApiClient.mustache
@@ -133,6 +133,13 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -287,6 +294,25 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -308,7 +334,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -322,7 +348,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -336,7 +362,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -350,7 +376,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -364,7 +390,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     {{#hasOAuthMethods}}
@@ -379,7 +405,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
                 return;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     {{/hasOAuthMethods}}
@@ -435,7 +461,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -502,8 +528,8 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch ({{#useJackson3}}JacksonException{{/useJackson3}}{{^useJackson3}}JsonProcessingException{{/useJackson3}} e) {
-                throw new RuntimeException(e);
+            } catch ({{#useJackson3}}JacksonException{{/useJackson3}}{{^useJackson3}}JsonProcessingException{{/useJackson3}} e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -512,7 +538,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch ({{#useJackson3}}JacksonException{{/useJackson3}}{{^useJackson3}}JsonProcessingException{{/useJackson3}} e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -821,7 +847,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/echo_api/java/restclient/.openapi-generator/FILES b/samples/client/echo_api/java/restclient/.openapi-generator/FILES
index 939acb947c39..e4f10b1adfc1 100644
--- a/samples/client/echo_api/java/restclient/.openapi-generator/FILES
+++ b/samples/client/echo_api/java/restclient/.openapi-generator/FILES
@@ -33,6 +33,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ApiClient.java
index 4cd8c4f7984d..3672c5a0c2c8 100644
--- a/samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ApiClient.java
@@ -97,6 +97,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -242,6 +249,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -263,7 +289,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -278,7 +304,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -292,7 +318,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -306,7 +332,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -320,7 +346,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -334,7 +360,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -389,7 +415,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -457,7 +483,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -466,7 +492,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -800,7 +826,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..32f899e95bfb
--- /dev/null
+++ b/samples/client/echo_api/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * Echo Server API
+ * Echo Server API
+ *
+ * The version of the OpenAPI document: 0.1.0
+ * Contact: team@openapitools.org
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/others/java/restclient-enum-in-multipart/.openapi-generator/FILES b/samples/client/others/java/restclient-enum-in-multipart/.openapi-generator/FILES
index 1ce4cca21cde..b19d56bcdd98 100644
--- a/samples/client/others/java/restclient-enum-in-multipart/.openapi-generator/FILES
+++ b/samples/client/others/java/restclient-enum-in-multipart/.openapi-generator/FILES
@@ -19,6 +19,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ApiClient.java
index a2d36a8ca35d..295d81237d8f 100644
--- a/samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ApiClient.java
@@ -97,6 +97,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -241,6 +248,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -262,7 +288,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -277,7 +303,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -291,7 +317,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -305,7 +331,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -319,7 +345,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -333,7 +359,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -388,7 +414,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -456,7 +482,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -465,7 +491,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -799,7 +825,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..b41b4f28c2d2
--- /dev/null
+++ b/samples/client/others/java/restclient-enum-in-multipart/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * API
+ * API
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/others/java/restclient-sealedInterface/.openapi-generator/FILES b/samples/client/others/java/restclient-sealedInterface/.openapi-generator/FILES
index 79e1f1f075fa..d11eb14c0d55 100644
--- a/samples/client/others/java/restclient-sealedInterface/.openapi-generator/FILES
+++ b/samples/client/others/java/restclient-sealedInterface/.openapi-generator/FILES
@@ -38,6 +38,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java
index 463913c837d0..0539f1b276f8 100644
--- a/samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java
@@ -97,6 +97,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -240,6 +247,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -261,7 +287,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -276,7 +302,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -290,7 +316,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -304,7 +330,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -318,7 +344,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -332,7 +358,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -387,7 +413,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -455,7 +481,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -464,7 +490,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -798,7 +824,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..abda53e96c04
--- /dev/null
+++ b/samples/client/others/java/restclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * ByRefOrValue
+ * This tests for a oneOf interface representation 
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/others/java/restclient-useAbstractionForFiles/.openapi-generator/FILES b/samples/client/others/java/restclient-useAbstractionForFiles/.openapi-generator/FILES
index 9078c63e26ab..0cc5234c597b 100644
--- a/samples/client/others/java/restclient-useAbstractionForFiles/.openapi-generator/FILES
+++ b/samples/client/others/java/restclient-useAbstractionForFiles/.openapi-generator/FILES
@@ -16,6 +16,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java
index 24004f99b7f7..379106f2da15 100644
--- a/samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java
@@ -97,6 +97,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -240,6 +247,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -261,7 +287,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -276,7 +302,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -290,7 +316,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -304,7 +330,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -318,7 +344,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -332,7 +358,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -387,7 +413,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -455,7 +481,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -464,7 +490,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -798,7 +824,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..c20b33da47e0
--- /dev/null
+++ b/samples/client/others/java/restclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * Response file abstraction test
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/others/java/webclient-sealedInterface/.openapi-generator/FILES b/samples/client/others/java/webclient-sealedInterface/.openapi-generator/FILES
index 79e1f1f075fa..d11eb14c0d55 100644
--- a/samples/client/others/java/webclient-sealedInterface/.openapi-generator/FILES
+++ b/samples/client/others/java/webclient-sealedInterface/.openapi-generator/FILES
@@ -38,6 +38,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java
index 425d78b6670f..04c559f1ee7b 100644
--- a/samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ApiClient.java
@@ -109,6 +109,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -230,6 +237,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -251,7 +277,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -265,7 +291,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -279,7 +305,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -293,7 +319,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -307,7 +333,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -362,7 +388,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -429,8 +455,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -439,7 +465,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -743,7 +769,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..abda53e96c04
--- /dev/null
+++ b/samples/client/others/java/webclient-sealedInterface/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * ByRefOrValue
+ * This tests for a oneOf interface representation 
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/others/java/webclient-sealedInterface_3_1/.openapi-generator/FILES b/samples/client/others/java/webclient-sealedInterface_3_1/.openapi-generator/FILES
index 79e1f1f075fa..d11eb14c0d55 100644
--- a/samples/client/others/java/webclient-sealedInterface_3_1/.openapi-generator/FILES
+++ b/samples/client/others/java/webclient-sealedInterface_3_1/.openapi-generator/FILES
@@ -38,6 +38,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ApiClient.java
index 425d78b6670f..04c559f1ee7b 100644
--- a/samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ApiClient.java
@@ -109,6 +109,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -230,6 +237,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -251,7 +277,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -265,7 +291,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -279,7 +305,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -293,7 +319,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -307,7 +333,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -362,7 +388,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -429,8 +455,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -439,7 +465,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -743,7 +769,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..abda53e96c04
--- /dev/null
+++ b/samples/client/others/java/webclient-sealedInterface_3_1/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * ByRefOrValue
+ * This tests for a oneOf interface representation 
+ *
+ * The version of the OpenAPI document: 0.0.1
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/others/java/webclient-useAbstractionForFiles/.openapi-generator/FILES b/samples/client/others/java/webclient-useAbstractionForFiles/.openapi-generator/FILES
index 9078c63e26ab..0cc5234c597b 100644
--- a/samples/client/others/java/webclient-useAbstractionForFiles/.openapi-generator/FILES
+++ b/samples/client/others/java/webclient-useAbstractionForFiles/.openapi-generator/FILES
@@ -16,6 +16,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java
index 1fde9de1cf79..bb6d06a0a2f9 100644
--- a/samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ApiClient.java
@@ -109,6 +109,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -230,6 +237,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -251,7 +277,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -265,7 +291,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -279,7 +305,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -293,7 +319,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -307,7 +333,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -362,7 +388,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -429,8 +455,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -439,7 +465,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -743,7 +769,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..c20b33da47e0
--- /dev/null
+++ b/samples/client/others/java/webclient-useAbstractionForFiles/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * Response file abstraction test
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient-nullable-arrays/.openapi-generator/FILES b/samples/client/petstore/java/restclient-nullable-arrays/.openapi-generator/FILES
index eedafa945afd..1466503e3b79 100644
--- a/samples/client/petstore/java/restclient-nullable-arrays/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient-nullable-arrays/.openapi-generator/FILES
@@ -17,6 +17,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java
index f70c16ca989a..ac65442c5556 100644
--- a/samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java
@@ -97,6 +97,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -240,6 +247,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -261,7 +287,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -276,7 +302,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -290,7 +316,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -304,7 +330,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -318,7 +344,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -332,7 +358,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -387,7 +413,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -455,7 +481,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -464,7 +490,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -798,7 +824,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..c937922aaa4f
--- /dev/null
+++ b/samples/client/petstore/java/restclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * Minimal Example 
+ * byte Array error in equal method
+ *
+ * The version of the OpenAPI document: v1
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson2/.openapi-generator/FILES b/samples/client/petstore/java/restclient-springBoot4-jackson2/.openapi-generator/FILES
index 345da529f8a1..94cc6f4676ac 100644
--- a/samples/client/petstore/java/restclient-springBoot4-jackson2/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson2/.openapi-generator/FILES
@@ -19,6 +19,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ApiClient.java
index ee5a0f33e77d..da6ffdc29d6b 100644
--- a/samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ApiClient.java
@@ -98,6 +98,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -242,6 +249,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -263,7 +289,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -278,7 +304,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -292,7 +318,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -306,7 +332,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -320,7 +346,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -334,7 +360,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -358,7 +384,7 @@ public ApiClient setAccessToken(Supplier<String> tokenSupplier) {
                 return this;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -413,7 +439,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -481,7 +507,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -490,7 +516,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -824,7 +850,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..5df78a25612b
--- /dev/null
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson2/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES b/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES
index 399326b1defb..0360f20c7340 100644
--- a/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES
@@ -17,6 +17,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/ServerConfiguration.java
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java
index 4ca008ddb39b..b746bc9ca3e8 100644
--- a/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java
@@ -96,6 +96,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final JsonMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -233,6 +240,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -254,7 +280,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -269,7 +295,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -283,7 +309,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -297,7 +323,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -311,7 +337,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -325,7 +351,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -380,7 +406,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -448,7 +474,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JacksonException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -457,7 +483,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JacksonException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -791,7 +817,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..e759561ae897
--- /dev/null
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * jspecify
+ * test fully qualified name and jspecify
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson3/.openapi-generator/FILES b/samples/client/petstore/java/restclient-springBoot4-jackson3/.openapi-generator/FILES
index 389fe62eaae9..9676ccd030da 100644
--- a/samples/client/petstore/java/restclient-springBoot4-jackson3/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson3/.openapi-generator/FILES
@@ -19,6 +19,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/ServerConfiguration.java
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java
index b521b16abd32..ff214cba8b61 100644
--- a/samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java
@@ -97,6 +97,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final JsonMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -235,6 +242,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -256,7 +282,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -271,7 +297,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -285,7 +311,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -299,7 +325,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -313,7 +339,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -327,7 +353,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -351,7 +377,7 @@ public ApiClient setAccessToken(Supplier<String> tokenSupplier) {
                 return this;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -406,7 +432,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -474,7 +500,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JacksonException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -483,7 +509,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JacksonException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -817,7 +843,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..5df78a25612b
--- /dev/null
+++ b/samples/client/petstore/java/restclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient-swagger2/.openapi-generator/FILES b/samples/client/petstore/java/restclient-swagger2/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/restclient-swagger2/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient-swagger2/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java
index f773ee249976..ba9fc446b26a 100644
--- a/samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java
@@ -141,6 +141,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -289,6 +296,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -310,7 +336,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -325,7 +351,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -339,7 +365,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -353,7 +379,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -367,7 +393,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -381,7 +407,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -405,7 +431,7 @@ public ApiClient setAccessToken(Supplier<String> tokenSupplier) {
                 return this;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -460,7 +486,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -528,7 +554,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -537,7 +563,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -871,7 +897,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/restclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient-useSingleRequestParameter-static/.openapi-generator/FILES b/samples/client/petstore/java/restclient-useSingleRequestParameter-static/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/restclient-useSingleRequestParameter-static/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient-useSingleRequestParameter-static/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ApiClient.java
index f773ee249976..ba9fc446b26a 100644
--- a/samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ApiClient.java
@@ -141,6 +141,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -289,6 +296,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -310,7 +336,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -325,7 +351,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -339,7 +365,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -353,7 +379,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -367,7 +393,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -381,7 +407,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -405,7 +431,7 @@ public ApiClient setAccessToken(Supplier<String> tokenSupplier) {
                 return this;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -460,7 +486,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -528,7 +554,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -537,7 +563,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -871,7 +897,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/restclient-useSingleRequestParameter-static/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient-useSingleRequestParameter/.openapi-generator/FILES b/samples/client/petstore/java/restclient-useSingleRequestParameter/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/restclient-useSingleRequestParameter/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient-useSingleRequestParameter/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java
index f773ee249976..ba9fc446b26a 100644
--- a/samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java
@@ -141,6 +141,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -289,6 +296,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -310,7 +336,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -325,7 +351,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -339,7 +365,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -353,7 +379,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -367,7 +393,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -381,7 +407,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -405,7 +431,7 @@ public ApiClient setAccessToken(Supplier<String> tokenSupplier) {
                 return this;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -460,7 +486,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -528,7 +554,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -537,7 +563,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -871,7 +897,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/restclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/restclient/.openapi-generator/FILES b/samples/client/petstore/java/restclient/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/restclient/.openapi-generator/FILES
+++ b/samples/client/petstore/java/restclient/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ApiClient.java
index f773ee249976..ba9fc446b26a 100644
--- a/samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ApiClient.java
@@ -141,6 +141,13 @@ protected String collectionToString(Collection<?> collection) {
     protected final ObjectMapper mapper;
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this(null);
@@ -289,6 +296,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -310,7 +336,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -325,7 +351,7 @@ public void setBearerToken(Supplier<String> tokenSupplier) {
             return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -339,7 +365,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -353,7 +379,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -367,7 +393,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -381,7 +407,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -405,7 +431,7 @@ public ApiClient setAccessToken(Supplier<String> tokenSupplier) {
                 return this;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -460,7 +486,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -528,7 +554,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -537,7 +563,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -871,7 +897,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/restclient/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/webclient-jakarta/.openapi-generator/FILES b/samples/client/petstore/java/webclient-jakarta/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/webclient-jakarta/.openapi-generator/FILES
+++ b/samples/client/petstore/java/webclient-jakarta/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ApiClient.java
index 9490dcf43075..ed3bfb7bc562 100644
--- a/samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ApiClient.java
@@ -110,6 +110,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -236,6 +243,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -257,7 +283,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -271,7 +297,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -285,7 +311,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -299,7 +325,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -313,7 +339,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -327,7 +353,7 @@ public void setAccessToken(String accessToken) {
                 return;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -382,7 +408,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -449,8 +475,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -459,7 +485,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -763,7 +789,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/webclient-jakarta/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/webclient-nullable-arrays/.openapi-generator/FILES b/samples/client/petstore/java/webclient-nullable-arrays/.openapi-generator/FILES
index eedafa945afd..1466503e3b79 100644
--- a/samples/client/petstore/java/webclient-nullable-arrays/.openapi-generator/FILES
+++ b/samples/client/petstore/java/webclient-nullable-arrays/.openapi-generator/FILES
@@ -17,6 +17,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java
index 41bcc01749e7..2e3977a90497 100644
--- a/samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ApiClient.java
@@ -109,6 +109,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -230,6 +237,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -251,7 +277,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -265,7 +291,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -279,7 +305,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -293,7 +319,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -307,7 +333,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -362,7 +388,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -429,8 +455,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -439,7 +465,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -743,7 +769,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..c937922aaa4f
--- /dev/null
+++ b/samples/client/petstore/java/webclient-nullable-arrays/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * Minimal Example 
+ * byte Array error in equal method
+ *
+ * The version of the OpenAPI document: v1
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES b/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES
index d59cb3fdbb35..fa0830b314a4 100644
--- a/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES
+++ b/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/.openapi-generator/FILES
@@ -17,6 +17,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java
index de847d3ee896..b30e50883e2f 100644
--- a/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ApiClient.java
@@ -107,6 +107,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -222,6 +229,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -243,7 +269,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -257,7 +283,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -271,7 +297,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -285,7 +311,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -299,7 +325,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -354,7 +380,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -421,8 +447,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JacksonException e) {
-                throw new RuntimeException(e);
+            } catch (JacksonException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -431,7 +457,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JacksonException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -735,7 +761,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..e759561ae897
--- /dev/null
+++ b/samples/client/petstore/java/webclient-springBoot4-jackson3-jspecify/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * jspecify
+ * test fully qualified name and jspecify
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/webclient-springBoot4-jackson3/.openapi-generator/FILES b/samples/client/petstore/java/webclient-springBoot4-jackson3/.openapi-generator/FILES
index 345da529f8a1..94cc6f4676ac 100644
--- a/samples/client/petstore/java/webclient-springBoot4-jackson3/.openapi-generator/FILES
+++ b/samples/client/petstore/java/webclient-springBoot4-jackson3/.openapi-generator/FILES
@@ -19,6 +19,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java
index 2d4f52eae16b..dbda70badc9d 100644
--- a/samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ApiClient.java
@@ -108,6 +108,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -224,6 +231,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -245,7 +271,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -259,7 +285,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -273,7 +299,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -287,7 +313,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -301,7 +327,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -315,7 +341,7 @@ public void setAccessToken(String accessToken) {
                 return;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -370,7 +396,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -437,8 +463,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JacksonException e) {
-                throw new RuntimeException(e);
+            } catch (JacksonException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -447,7 +473,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JacksonException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -751,7 +777,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..5df78a25612b
--- /dev/null
+++ b/samples/client/petstore/java/webclient-springBoot4-jackson3/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/webclient-swagger2/.openapi-generator/FILES b/samples/client/petstore/java/webclient-swagger2/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/webclient-swagger2/.openapi-generator/FILES
+++ b/samples/client/petstore/java/webclient-swagger2/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java
index f7f65e1c23d4..d81de1a1b88d 100644
--- a/samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ApiClient.java
@@ -110,6 +110,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -236,6 +243,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -257,7 +283,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -271,7 +297,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -285,7 +311,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -299,7 +325,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -313,7 +339,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -327,7 +353,7 @@ public void setAccessToken(String accessToken) {
                 return;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -382,7 +408,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -449,8 +475,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -459,7 +485,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -763,7 +789,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/webclient-swagger2/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/webclient-useSingleRequestParameter/.openapi-generator/FILES b/samples/client/petstore/java/webclient-useSingleRequestParameter/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/webclient-useSingleRequestParameter/.openapi-generator/FILES
+++ b/samples/client/petstore/java/webclient-useSingleRequestParameter/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java
index f7f65e1c23d4..d81de1a1b88d 100644
--- a/samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ApiClient.java
@@ -110,6 +110,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -236,6 +243,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -257,7 +283,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -271,7 +297,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -285,7 +311,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -299,7 +325,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -313,7 +339,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -327,7 +353,7 @@ public void setAccessToken(String accessToken) {
                 return;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -382,7 +408,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -449,8 +475,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -459,7 +485,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -763,7 +789,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/webclient-useSingleRequestParameter/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file
diff --git a/samples/client/petstore/java/webclient/.openapi-generator/FILES b/samples/client/petstore/java/webclient/.openapi-generator/FILES
index 555600856098..d7a6d76bf38f 100644
--- a/samples/client/petstore/java/webclient/.openapi-generator/FILES
+++ b/samples/client/petstore/java/webclient/.openapi-generator/FILES
@@ -72,6 +72,7 @@ pom.xml
 settings.gradle
 src/main/AndroidManifest.xml
 src/main/java/org/openapitools/client/ApiClient.java
+src/main/java/org/openapitools/client/ExceptionProvider.java
 src/main/java/org/openapitools/client/JavaTimeFormatter.java
 src/main/java/org/openapitools/client/RFC3339DateFormat.java
 src/main/java/org/openapitools/client/RFC3339InstantDeserializer.java
diff --git a/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java
index f7f65e1c23d4..d81de1a1b88d 100644
--- a/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ApiClient.java
@@ -110,6 +110,13 @@ protected String collectionToString(Collection<?> collection) {
 
     protected Map<String, Authentication> authentications;
 
+    /**
+     * The {@link ExceptionProvider} used to create exceptions thrown by this client.
+     * Defaults to {@link ExceptionProvider#DEFAULT}. Can be replaced to customize the exceptions
+     * thrown by this client by calling {@link #setExceptionProvider(ExceptionProvider)}.
+     */
+    protected ExceptionProvider exceptionProvider = ExceptionProvider.DEFAULT;
+
 
     public ApiClient() {
         this.dateFormat = createDefaultDateFormat();
@@ -236,6 +243,25 @@ public Map<String, Authentication> getAuthentications() {
         return authentications;
     }
 
+    /**
+     * Get the current {@link ExceptionProvider}.
+     * @return the exception provider
+     */
+    public ExceptionProvider getExceptionProvider() {
+        return exceptionProvider;
+    }
+
+    /**
+     * Set a custom {@link ExceptionProvider} to control which exception types are thrown
+     * by this client.
+     * @param exceptionProvider the exception provider
+     * @return this client instance
+     */
+    public ApiClient setExceptionProvider(ExceptionProvider exceptionProvider) {
+        this.exceptionProvider = exceptionProvider;
+        return this;
+    }
+
     /**
      * Get authentication for the given name.
      *
@@ -257,7 +283,7 @@ public void setBearerToken(String bearerToken) {
                 return;
             }
         }
-        throw new RuntimeException("No Bearer authentication configured!");
+        throw exceptionProvider.bearerAuthException();
     }
 
     /**
@@ -271,7 +297,7 @@ public void setUsername(String username) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -285,7 +311,7 @@ public void setPassword(String password) {
                 return;
             }
         }
-        throw new RuntimeException("No HTTP basic authentication configured!");
+        throw exceptionProvider.httpBasicAuthException();
     }
 
     /**
@@ -299,7 +325,7 @@ public void setApiKey(String apiKey) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -313,7 +339,7 @@ public void setApiKeyPrefix(String apiKeyPrefix) {
                 return;
             }
         }
-        throw new RuntimeException("No API key authentication configured!");
+        throw exceptionProvider.apiKeyAuthException();
     }
 
     /**
@@ -327,7 +353,7 @@ public void setAccessToken(String accessToken) {
                 return;
             }
         }
-        throw new RuntimeException("No OAuth2 authentication configured!");
+        throw exceptionProvider.oAuth2Exception();
     }
 
     /**
@@ -382,7 +408,7 @@ public Date parseDate(String str) {
         try {
             return dateFormat.parse(str);
         } catch (ParseException e) {
-            throw new RuntimeException(e);
+            throw exceptionProvider.dateTimeException(e);
         }
     }
 
@@ -449,8 +475,8 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
         } else {
             try {
                 return parameterToMultiValueMap(collectionFormat, name, mapper.writeValueAsString(value));
-           } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+            } catch (JsonProcessingException e) {
+                throw exceptionProvider.jacksonException(e);
             }
         }
 
@@ -459,7 +485,7 @@ public MultiValueMap<String, String> parameterToMultiValueMapJson(CollectionForm
             try {
                 values.add(mapper.writeValueAsString(o));
             } catch (JsonProcessingException e) {
-                throw new RuntimeException(e);
+                throw exceptionProvider.jacksonException(e);
             }
         }
         return parameterToMultiValueMap(collectionFormat, name, "[" + StringUtils.collectionToDelimitedString(values, collectionFormat.separator) + "]");
@@ -763,7 +789,7 @@ protected void updateParamsForAuth(String[] authNames, MultiValueMap<String, Str
         for (String authName : authNames) {
             Authentication auth = authentications.get(authName);
             if (auth == null) {
-                throw new RestClientException("Authentication undefined: " + authName);
+                throw exceptionProvider.undefinedAuthenticationException(authName);
             }
             auth.applyToParams(queryParams, headerParams, cookieParams);
         }
diff --git a/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ExceptionProvider.java b/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ExceptionProvider.java
new file mode 100644
index 000000000000..2863da831dd2
--- /dev/null
+++ b/samples/client/petstore/java/webclient/src/main/java/org/openapitools/client/ExceptionProvider.java
@@ -0,0 +1,79 @@
+/*
+ * OpenAPI Petstore
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * 
+ *
+ * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
+ * https://openapi-generator.tech
+ * Do not edit the class manually.
+ */
+
+
+package org.openapitools.client;
+
+import org.springframework.web.client.RestClientException;
+import java.text.ParseException;
+
+/**
+ * Extension point for customizing exceptions thrown by the generated API client.
+ * <p>
+ * The default implementation throws {@link RuntimeException}. To use custom exception
+ * types, implement this interface and pass the instance to
+ * {@link ApiClient#setExceptionProvider(ExceptionProvider)}.
+ * </p>
+ * <pre>{@code
+ * apiClient.setExceptionProvider(new ExceptionProvider() {
+ *     public RuntimeException bearerAuthException() {
+ *         return new MyAuthException("No Bearer authentication configured!");
+ *     }
+ * });
+ * }</pre>
+ */
+public interface ExceptionProvider {
+
+    /** Returns an exception indicating that no Bearer authentication is configured. */
+    default RuntimeException bearerAuthException() {
+        return new RuntimeException("No Bearer authentication configured!");
+    }
+
+    /** Returns an exception indicating that no HTTP basic authentication is configured. */
+    default RuntimeException httpBasicAuthException() {
+        return new RuntimeException("No HTTP basic authentication configured!");
+    }
+
+    /** Returns an exception indicating that no API key authentication is configured. */
+    default RuntimeException apiKeyAuthException() {
+        return new RuntimeException("No API key authentication configured!");
+    }
+
+    /** Returns an exception indicating that no OAuth2 authentication is configured. */
+    default RuntimeException oAuth2Exception() {
+        return new RuntimeException("No OAuth2 authentication configured!");
+    }
+
+    /** Wraps a date/time parse exception. */
+    default RuntimeException dateTimeException(ParseException e) {
+        return new RuntimeException(e);
+    }
+
+    /** Wraps a Jackson serialization/deserialization exception. */
+    default RuntimeException jacksonException(Exception e) {
+        return new RuntimeException(e);
+    }
+
+    /**
+     * Returns an exception indicating that the requested authentication scheme is not configured.
+     *
+     * @param authName the name of the authentication scheme that could not be found
+     * @return a {@link RestClientException} describing the missing authentication
+     */
+    default RestClientException undefinedAuthenticationException(String authName) {
+        return new RestClientException("Authentication undefined: " + authName);
+    }
+
+    /** The default {@link ExceptionProvider} instance. */
+    ExceptionProvider DEFAULT = new ExceptionProvider() {};
+
+}
\ No newline at end of file