private boolean insertChild(Object parent,Object child){
  Set children=(Set)fChildrenMap.get(parent);
  if (children == null) {
    children=new HashSet();
    fChildrenMap.put(parent,children);
  }
  return children.add(child);
}

private boolean insertChild ( Object parent , Object child ) { Set children = ( Set ) fChildrenMap . get ( parent ) ; if ( children == null ) { children = new HashSet ( ) ; fChildrenMap . put ( parent , children ) ; } return children . add ( child ) ; }
adds the child to the parent .
