code: public Observable<BuildTaskInner> beginCreateAsync(String resourceGroupName, String registryName, String buildTaskName, BuildTaskInner buildTaskCreateParameters) {
          return beginCreateWithServiceResponseAsync(resourceGroupName, registryName, buildTaskName, buildTaskCreateParameters).map(new Func1<ServiceResponse<BuildTaskInner>, BuildTaskInner>() {
              @Override
              public BuildTaskInner call(ServiceResponse<BuildTaskInner> response) {
                  return response.body();
              }
          });
      }
docs: Creates a build task for a container registry with the specified parameters.
  
  @param resourceGroupName The name of the resource group to which the container registry belongs.
  @param registryName The name of the container registry.
  @param buildTaskName The name of the container registry build task.
  @param buildTaskCreateParameters The parameters for creating a build task.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the BuildTaskInner object