void deleteChild(PolicyNode childNode){
  if (isImmutable) {
    throw new IllegalStateException("PolicyNode is immutable");
  }
  mChildren.remove(childNode);
}

void deleteChild ( PolicyNode childNode ) { if ( isImmutable ) { throw new IllegalStateException ( "PolicyNode is immutable" ) ; } mChildren . remove ( childNode ) ; }
deletes the specified child node of this node , if it exists .
