code: protected final void initializeMediaUpload(AbstractInputStreamContent mediaContent) {
      HttpRequestFactory requestFactory = abstractGoogleClient.getRequestFactory();
      this.uploader = new MediaHttpUploader(
          mediaContent, requestFactory.getTransport(), requestFactory.getInitializer());
      this.uploader.setInitiationRequestMethod(requestMethod);
      if (httpContent != null) {
        this.uploader.setMetadata(httpContent);
      }
    }
docs: Initializes the media HTTP uploader based on the media content.
  
  @param mediaContent media content