code: public Response handle(boolean pretty) throws WebApplicationException
      {
          try
          {
              // Call Authlete's /api/service/configuration API.
              // The API returns a JSON that complies with
              // OpenID Connect Discovery 1.0.
              String json = getApiCaller().callServiceConfiguration(pretty);
  
              // Response as "application/json;charset=UTF-8" with 200 OK.
              return ResponseUtil.ok(json);
          }
          catch (WebApplicationException e)
          {
              // The API call raised an exception.
              throw e;
          }
          catch (Throwable t)
          {
              // Unexpected error.
              throw unexpected("Unexpected error in ConfigurationRequestHandler", t);
          }
      }
docs: Handle a request to an OpenID Provider configuration endpoint. This
  method internally calls Authlete's {@code /api/service/configuration}
  API.
  
  @param pretty
  {@code true} to return the output JSON in pretty format.
  
  @return
  A response that should be returned from the endpoint to
  the client application.
  
  @throws WebApplicationException
  An error occurred.