public void add(RefEntity child) {
    if (myChildren == null) {
      myChildren = new ArrayList<RefEntity>();
    }

    myChildren.add(child);
    ((RefEntityImpl) child).setOwner(this);
  }
 protected void removeChild(RefEntity child) {
   if (myChildren != null) {
     myChildren.remove(child);
     ((RefEntityImpl) child).setOwner(null);
   }
 }