code: private void preSave(Group group, boolean isNew) throws Exception
     {
        for (GroupEventListener listener : listeners)
        {
           listener.preSave(group, isNew);
        }
     }
docs: Notifying listeners before group creation.
  
  @param group
  the group which is used in create operation
  @param isNew
  true, if we have a deal with new group, otherwise it is false
  which mean update operation is in progress
  @throws Exception
  if any listener failed to handle the event