code: public static void addActors(final Stage stage, final Iterable<Actor> actors) {
          if (actors != null) {
              for (final Actor actor : actors) {
                  stage.addActor(actor);
              }
          }
      }
docs: Null-safe utility for adding multiple actors to the stage.
  
  @param stage will contain the actors.
  @param actors will be added to the stage. Can be null.