code: public Observable<Void> cancelAsync(String resourceGroupName, String registryName, String buildId) {
          return cancelWithServiceResponseAsync(resourceGroupName, registryName, buildId).map(new Func1<ServiceResponse<Void>, Void>() {
              @Override
              public Void call(ServiceResponse<Void> response) {
                  return response.body();
              }
          });
      }
docs: Cancel an existing build.
  
  @param resourceGroupName The name of the resource group to which the container registry belongs.
  @param registryName The name of the container registry.
  @param buildId The build ID.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request