@Override
        public boolean update(DnDEvent event) {
          @SuppressWarnings("unchecked") Set<String> oldGroupNames = getAllGroups((Map<TemplateImpl, DefaultMutableTreeNode>)event.getAttachedObject());
          TemplateGroup group = getDropGroup(event);
          boolean differentGroup = group != null && !oldGroupNames.contains(group.getName());
          event.setDropPossible(differentGroup, "");
          return true;
        }
@Override
        public boolean update(DnDEvent event)