}
  public void finish()  {    int count;    synchronized (this) {      count = --_useCount;    }    if (count > 0)      return;    if (count < 0)      throw new IllegalStateException();    try {      ClusterObject clusterObject = _clusterObject;      if (clusterObject != null)        clusterObject.store(this);    } catch (Throwable e) {      log.log(Level.WARNING, "Can't serialize session", e);    }  }