@Override public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
  this.id=DBIDUtil.importInteger(in.readInt());
}

@ Override public void readExternal ( ObjectInput in ) throws IOException , ClassNotFoundException { this . id = DBIDUtil . importInteger ( in . readInt ( ) ) ; }
restores the id of the object ( node or data object ) that is represented by this entry from the specified stream .
