docs(api): add Swagger @ApiResponses for OAuthClientController

[Shivamrut]

Works on: #2565

Summary

• Added @Operation, @ApiResponses, @Tag, and @SecurityRequirement annotations to all 3 endpoints in OAuthClientController (GET, POST, DELETE)
• Documented response codes: 200, 400, 401, 403, 500 based on actual return paths in the code
• Added springdoc-openapi-starter-webmvc-ui dependency to the authorization-server module's pom.xml (same pattern as resource-server)

Files Changed

• rest/authorization-server/pom.xml — added springdoc-openapi dependency
• rest/authorization-server/src/.../OAuthClientController.java — added Swagger annotations

Test Plan

• mvn clean install -pl rest/authorization-server -am -DskipTests — BUILD SUCCESS
• mvn test -pl rest/authorization-server — 12 tests run, 0 failures, 0 errors

Issue: #2565

[Shivamrut]

@GMishx @amritkv @KoukiHama Please review this PR, I have tested the build and unit test case, everything pass. Any changes please let me know

[GMishx]

The documentation for authorization-server does not appear in http://localhost:8080/resource/swagger-ui/index.html

Not sure this PR in current state would be helpful in any manner.

[Shivamrut]

Thanks for the feedback, @GMishx.
You’re right this PR adds OpenAPI annotations in authorization-server, so they won’t show up in resource-server Swagger (/resource/swagger-ui/index.html).

Could you please confirm the expected direction so I can update this correctly?

1. Should auth-server APIs be documented in a separate auth-server Swagger endpoint, or
2. Should they be aggregated and shown inside resource-server Swagger UI?

Also, one clarification from my side: do we want auth-server Swagger to be publicly useful for users/integrators (e.g., OAuth client-management endpoints), or is documenting only resource-server APIs the intended scope?

If option 1, I’ll update this PR to make auth-server Swagger endpoints accessible and share the exact URL here.
If option 2, I can either extend this PR for aggregation or open a follow-up PR, based on your preference.