code: private void notifyOnPreferenceFragmentShown(
              @NonNull final NavigationPreference navigationPreference,
              @NonNull final Fragment fragment) {
          for (PreferenceFragmentListener listener : preferenceFragmentListeners) {
              listener.onPreferenceFragmentShown(navigationPreference, fragment);
          }
      }
docs: Notifies all registered listeners that a preference fragment has been shown.
  
  @param navigationPreference
  The navigation preference, the fragment, which has been shown, is associated with, as
  an instance of the class {@link NavigationPreference}. The navigation preference may
  not be null
  @param fragment
  The fragment, which has been shown, as an instance of the class Fragment. The
  fragment may not be null