docs: public Observable<ImageInner> beginUpdateAsync(String resourceGroupName, String imageName, ImageUpdate parameters) {
          return beginUpdateWithServiceResponseAsync(resourceGroupName, imageName, parameters).map(new Func1<ServiceResponse<ImageInner>, ImageInner>() {
              @Override
              public ImageInner call(ServiceResponse<ImageInner> response) {
                  return response.body();
              }
          });
      }