@Override public int addRef(Object ref){
  if (_refs == null)   _refs=new ArrayList();
  _refs.add(ref);
  return _refs.size() - 1;
}

@ Override public int addRef ( Object ref ) { if ( _refs == null ) _refs = new ArrayList ( ) ; _refs . add ( ref ) ; return _refs . size ( ) - 1 ; }
adds a list / map reference .
