[BUG] Auto-Generated API interface should have only one method for API

I am using openapi-generator-maven-plugin 4.3.1 and spring boot 2.3.1.RELEASE for my microservice.

I am facing the issue where OpenAPI auto generated interface is not working with Spring Aspect.

I have a service class which implements two interfaces where one interface SecurityUserApi.java is auto generated by openapi-generator-maven-plugin and second interface UserController.java is manually created.

Here Aspect is working for the API implementation of manually created interface and not working for API implementation of OpenAPI generated interface.

### ISSUE:
As far as I have seen, in auto generated class there are two methods, one is _getUsers2 and other is getUsers2. Where getUsers2 has the comments // Override this method. But this method is called directly in _getUsers2, hence it will not be handled by aspect interceptor. If I override _getUser2 method then Aspect is working fine.

There should be only one method for an API in auto generated interface. Then this issue will be fixed.

RoleAccessAspect.java

@Aspect
@Configuration
@EnableAspectJAutoProxy(proxyTargetClass = true)
public class RoleAccessAspect {

@Around(ASPECT_CONDITION)
  public Object before(final ProceedingJoinPoint joinPoint) throws Throwable {
     // Role access check
  }
}

UserService.java

@Service
@Tag(name = "Security User Mamangement", description = "Security User API's")
public class UserService extends BaseService implements UserContoller, SecurityUserApi {

    @Override
    public ResponseEntity<Response> getUsers1(@RoleAccess(role = UserRoleEnum.USER_READ) final UUID authToken,
        final UUID userId) {
        // Business logic
    }

    @Override
    public ResponseEntity<Response> getUsers2(@RoleAccess(role = UserRoleEnum.USER_READ) final UUID authToken,
        final UUID userId) {
        // Business logic
    }
}

SecurityUserApi.java

@javax.annotation.Generated(value = "org.openapitools.codegen.languages.SpringCodegen", date = "2020-06-23T15:32:14.795+05:30[Asia/Kolkata]")
@Validated
@Api(value = "SecurityUser", description = "the SecurityUser API")
public interface SecurityUserApi {

    default Optional<NativeWebRequest> getRequest() {
        return Optional.empty();
    }

    /**
     * GET /user2 : View security users.
     * View an Security User
     *
     * @param authToken Authentication Key for Authentication and Authorization. this Authentication key obtained using Login API (required)
     * @param userId Id of the user to fetch. (optional)
     * @return User created Successfully (status code 201)
     *         or Request Failed (status code 400)
     *         or Unauthorized (status code 401)
     *         or Not Found (status code 404)
     *         or Internal Server Error (status code 500)
     */
    @ApiOperation(value = "View security users.", nickname = "getUsers2", notes = "View an Security User", response = Response.class, tags={ "SecurityUser", })
    @ApiResponses(value = { 
        @ApiResponse(code = 201, message = "User created Successfully", response = Response.class),
        @ApiResponse(code = 400, message = "Request Failed"),
        @ApiResponse(code = 401, message = "Unauthorized"),
        @ApiResponse(code = 404, message = "Not Found"),
        @ApiResponse(code = 500, message = "Internal Server Error") })
    @RequestMapping(value = "/user2",
        produces = { "application/json", "application/xml" }, 
        method = RequestMethod.GET)
    default ResponseEntity<Response> _getUsers2(@ApiParam(value = "Authentication Key for Authentication and Authorization. this Authentication key obtained using Login API" ,required=true) @RequestHeader(value="authToken", required=true) UUID authToken,@ApiParam(value = "Id of the user to fetch.") @Valid @RequestParam(value = "userId", required = false) UUID userId) {
        return getUsers(authToken, userId);
    }

    // Override this method
    default  ResponseEntity<Response> getUsers2(UUID authToken, UUID userId) {
        getRequest().ifPresent(request -> {
            for (MediaType mediaType: MediaType.parseMediaTypes(request.getHeader("Accept"))) {
                if (mediaType.isCompatibleWith(MediaType.valueOf("application/json"))) {
                    String exampleString = "{ \"message\" : \"message\", \"object\" : \"{}\" }";
                    ApiUtil.setExampleResponse(request, "application/json", exampleString);
                    break;
                }
                if (mediaType.isCompatibleWith(MediaType.valueOf("application/xml"))) {
                    String exampleString = "<null> <object>UNDEFINED_EXAMPLE_VALUE</object> <message>aeiou</message> </null>";
                    ApiUtil.setExampleResponse(request, "application/xml", exampleString);
                    break;
                }
            }
        });
        return new ResponseEntity<>(HttpStatus.NOT_IMPLEMENTED);
    }
}

UserContoller.java

@RestController
public interface UserContoller {

    @GetMapping(value = "/user1")
    ResponseEntity<Response> getUsers1(@RequestHeader(SecurityConstants.AUTH_TOKEN) UUID authToken,
        @RequestParam(required = false, name = "id") UUID userId);

}

Start with the generated SecurityUserApi.java and its implementation in UserService.java, then reproduce generation with openapi-generator-maven-plugin 4.3.1. Verify how _getUsers2 delegates to getUsers2 and confirm that the generated API exposes one overridable method whose invocation is intercepted by the aspect.