camel-sql: add javadoc to SqlOutputType enum constants (backport to 4.22.x)

components/camel-sql/src/main/java/org/apache/camel/component/sql/SqlOutputType.java

@@ -16,9 +16,35 @@
  */
 package org.apache.camel.component.sql;
 
+/**
+ * The type of output produced by the SQL producer and consumer for the result of a query.
+ */
 public enum SqlOutputType {
 
+    /**
+     * Returns the result of the query as a single object.
+     * <p>
+     * If the query has only a single column, the value of that column is returned (for example
+     * {@code SELECT COUNT(*) FROM PROJECT} returns a {@link Long}). If the query has more than one
+     * column, a {@link java.util.Map} of the row is returned. If {@code outputClass} is set, the row
+     * is instead converted into a Java bean of that type by calling the setters that match the column
+     * names; the class must have a default constructor.
+     * <p>
+     * If the query returns more than one row, a non-unique result exception is thrown.
+     */
     SelectOne,
+
+    /**
+     * Returns the result of the query as a {@link java.util.List} of {@link java.util.Map}, one map per
+     * row keyed by column name. If {@code outputClass} is set, each row is instead converted into a Java
+     * bean of that type by calling the setters that match the column names.
+     */
     SelectList,
+
+    /**
+     * Streams the result of the query using an {@link java.util.Iterator}, so rows are read from the
+     * {@link java.sql.ResultSet} lazily instead of being loaded into memory all at once. This can be
+     * combined with the Splitter EIP in streaming mode to process the result set in a streaming fashion.
+     */
     StreamList
 }