code: public Observable<ServiceResponse<Object>> getMetadataWithServiceResponseAsync(String appId) {
          if (appId == null) {
              throw new IllegalArgumentException("Parameter appId is required and cannot be null.");
          }
          return service.getMetadata(appId, this.client.acceptLanguage(), this.client.userAgent())
              .flatMap(new Func1<Response<ResponseBody>, Observable<ServiceResponse<Object>>>() {
                  @Override
                  public Observable<ServiceResponse<Object>> call(Response<ResponseBody> response) {
                      try {
                          ServiceResponse<Object> clientResponse = getMetadataDelegate(response);
                          return Observable.just(clientResponse);
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
docs: Retrieve metric metatadata.
  Gets metadata describing the available metrics.
  
  @param appId ID of the application. This is Application ID from the API Access settings blade in the Azure portal.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the Object object