@Override
    public boolean isDropPossible(@NotNull DnDEvent event) {
      Object attachedObject = event.getAttachedObject();
      if (attachedObject instanceof ShelvedChangeListDragBean) {
        return !((ShelvedChangeListDragBean)attachedObject).getShelvedChangelists().isEmpty();
      }
      return attachedObject instanceof ChangeListDragBean;
    }
@Override
    public boolean isDropPossible(@NotNull DnDEvent event)