[Bug]: Swagger/OpenAPI fails with Custom Auth in DAB 1.7.93: No authentication handler is registered for OAuthAuthentication

[mavg85]

What happened?

After upgrading Data API Builder from version 1.1.7 to 1.7.93, the Swagger UI no longer loads correctly when using Custom authentication with Auth0.

The Swagger page starts loading, but the OpenAPI endpoint fails. The DAB logs show an unhandled exception while requesting /api/openapi.

The same configuration works with DAB 1.1.7 for REST API calls using a valid Auth0 JWT token. In 1.1.7, Swagger UI loads, although Swagger UI does not seem to send the Authorization header when trying requests from the UI.

In DAB 1.7.93, /api/openapi fails before Swagger can be used.

Version

Data API Builder 1.7.93

Previous working version: 1.1.7

Authentication provider

Custom authentication with Auth0 JWT.

Relevant configuration:

{
  "data-source": {
    "database-type": "mssql",
    "connection-string": "@env('SQL_CONNECTION_STRING')"
  },
  "runtime": {
    "rest": {
      "enabled": true,
      "path": "/api"
    },
    "host": {
      "mode": "development",
      "authentication": {
        "provider": "Custom",
        "jwt": {
          "audience": "<AUTH0_API_IDENTIFIER>",
          "issuer": "https://<tenant>.eu.auth0.com/"
        }
      }
    }
  }
}

### Version

1.7.93

### What database are you using?

MSSQL

### What hosting model are you using?

Local (including CLI)

### Which API approach are you accessing DAB through?

REST

### Relevant log output

```Text
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/1.1 GET http://localhost:5000/api/maquinas - - -
dbug: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware[3]
      The request path  does not match the path filter
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1001]
      1 candidate(s) found for the request path '/api/maquinas'
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1005]
      Endpoint 'Azure.DataApiBuilder.Service.Controllers.RestController.Find (Azure.DataApiBuilder.Service)' with route pattern '{*route}' is valid for the request path '/api/maquinas'
dbug: Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware[1]
      Request matched endpoint 'Azure.DataApiBuilder.Service.Controllers.RestController.Find (Azure.DataApiBuilder.Service)'
fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HNLFV59JKKLV", Request id "0HNLFV59JKKLV:00000001": An unhandled exception was thrown by the application.
      System.InvalidOperationException: No authentication handler is registered for the scheme 'OAuthAuthentication'. The registered schemes are: StaticWebAppsAuthentication, AppServiceAuthentication, Bearer, SimulatorAuthentication. Did you forget to call AddAuthentication().Add[SomeAuthHandler]("OAuthAuthentication",...)?
         at Microsoft.AspNetCore.Authentication.AuthenticationService.AuthenticateAsync(HttpContext context, String scheme)
         at Azure.DataApiBuilder.Core.AuthenticationHelpers.ClientRoleHeaderAuthenticationMiddleware.InvokeAsync(HttpContext httpContext) in /_/src/Core/AuthenticationHelpers/ClientRoleHeaderAuthenticationMiddleware.cs:line 76
         at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
         at Azure.DataApiBuilder.Service.Startup.<>c__DisplayClass23_0.<<Configure>b__5>d.MoveNext() in /_/src/Service/Startup.cs:line 669
      --- End of stack trace from previous location ---
         at Swashbuckle.AspNetCore.SwaggerUI.SwaggerUIMiddleware.Invoke(HttpContext httpContext)
         at Azure.DataApiBuilder.Core.Services.PathRewriteMiddleware.InvokeAsync(HttpContext httpContext) in /_/src/Core/Services/PathRewriteMiddleware.cs:line 89
         at Azure.DataApiBuilder.Core.Services.CorrelationIdMiddleware.Invoke(HttpContext httpContext) in /_/src/Core/Services/CorrelationIdMiddleware.cs:line 53
         at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)
dbug: Microsoft.AspNetCore.Server.Kestrel.Connections[9]
      Connection id "0HNLFV59JKKLV" completed keep alive response.
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
      Request finished HTTP/1.1 GET http://localhost:5000/api/maquinas - 500 0 - 5.6669ms

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