code: public final BatchRequest batch(HttpRequestInitializer httpRequestInitializer) {
      BatchRequest batch =
          new BatchRequest(getRequestFactory().getTransport(), httpRequestInitializer);
      if (Strings.isNullOrEmpty(batchPath)) {
        batch.setBatchUrl(new GenericUrl(getRootUrl() + "batch"));
      } else {
        batch.setBatchUrl(new GenericUrl(getRootUrl() + batchPath));
      }
      return batch;
    }
docs: Create an {@link BatchRequest} object from this Google API client instance.
  
  <p>
  Sample usage:
  </p>
  
  <pre>
  client.batch(httpRequestInitializer)
  .queue(...)
  .queue(...)
  .execute();
  </pre>
  
  @param httpRequestInitializer The initializer to use when creating the top-level batch HTTP
  request or {@code null} for none
  @return newly created Batch request