code: private void updateAdd()
      {
          if (willAdd)
          {
              for (final Featurable featurable : toAdd)
              {
                  featurables.add(featurable);
                  for (final HandlerListener listener : listeners)
                  {
                      listener.notifyHandlableAdded(featurable);
                  }
                  if (featurable.hasFeature(Transformable.class))
                  {
                      final Transformable transformable = featurable.getFeature(Transformable.class);
                      transformable.teleport(transformable.getX(), transformable.getY());
                  }
              }
              toAdd.clear();
              willAdd = false;
          }
      }
docs: Update the add list. Prepare features, add to main list and notify listeners.