code: @Beta
    public Future<HttpResponse> executeAsync() {
      return executeAsync(
          Executors.newFixedThreadPool(1, new ThreadFactoryBuilder().setDaemon(true).build()));
    }
docs: {@link Beta} <br>
  Executes this request asynchronously using {@link #executeAsync(Executor)} in a single separate
  thread using {@link Executors#newFixedThreadPool(1)}.
  
  @return A future for accessing the results of the asynchronous request.
  @since 1.13