code: private Notification buildNotification() {
          Notification notification = mNotificationBuilder.build();
          if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
              notification.bigContentView = mNotificationExpandedView;
          }
          return notification;
      }
docs: Build the notification with the internal {@link android.app.Notification.Builder}
  
  @return notification ready to be displayed.