code: public Observable<BuildStepInner> createAsync(String resourceGroupName, String registryName, String buildTaskName, String stepName, BuildStepProperties properties) {
          return createWithServiceResponseAsync(resourceGroupName, registryName, buildTaskName, stepName, properties).map(new Func1<ServiceResponse<BuildStepInner>, BuildStepInner>() {
              @Override
              public BuildStepInner call(ServiceResponse<BuildStepInner> response) {
                  return response.body();
              }
          });
      }
docs: Creates a build step for a 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.
  @param stepName The name of a build step for a container registry build task.
  @param properties The properties of a build step.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request