code: public Observable<Page<BuildStepInner>> listAsync(final String resourceGroupName, final String registryName, final String buildTaskName) {
          return listWithServiceResponseAsync(resourceGroupName, registryName, buildTaskName)
              .map(new Func1<ServiceResponse<Page<BuildStepInner>>, Page<BuildStepInner>>() {
                  @Override
                  public Page<BuildStepInner> call(ServiceResponse<Page<BuildStepInner>> response) {
                      return response.body();
                  }
              });
      }
docs: List all the build steps for a given build task.
  
  @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.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the PagedList&lt;BuildStepInner&gt; object