code: @Override
      public HttpResponse loginFailed(ServiceRequestContext ctx, AggregatedHttpMessage req,
                                      @Nullable MessageContext<Response> message, Throwable cause) {
          return HttpResponse.of(HttpStatus.UNAUTHORIZED, MediaType.HTML_UTF_8,
                                 "<html><body>Login failed.</body></html>");
      }
docs: Invoked when a single sign-on request is rejected from the identity provider.