code: private void notifyOnNavigationPreferenceAdded(
              @NonNull final NavigationPreference navigationPreference) {
          for (NavigationListener listener : navigationListeners) {
              listener.onNavigationPreferenceAdded(navigationPreference);
          }
      }
docs: Notifies all registered listeners, that a navigation preference has been added to the
  activity.
  
  @param navigationPreference
  The navigation preference, which has been added, as an instance of the class {@link
  NavigationPreference}. The navigation preference may not be null