code: private void handleShowButtonBarIntent(@NonNull final Bundle extras) {
          if (extras.containsKey(EXTRA_SHOW_BUTTON_BAR)) {
              showButtonBar(extras.getBoolean(EXTRA_SHOW_BUTTON_BAR));
          }
      }
docs: Handles the intent extra, which specifies, whether the button bar should be shown, or not.
  
  @param extras
  The extras of the intent, which has been used to start the activity, as an instance
  of the class {@link Bundle}. The bundle may not be null