/**
  * Removes the given <tt>HistoryQueryListener</tt> from the list of listeners interested in query
  * result changes.
  *
  * @param l the <tt>HistoryQueryListener</tt> to remove
  */
 public void removeHistoryRecordsListener(HistoryQueryListener l) {
   synchronized (queryListeners) {
     queryListeners.remove(l);
   }
 }
  /**
   * Adds the given <tt>HistoryRecord</tt> to the result list of this query and notifies all
   * interested listeners that a new record is received.
   *
   * @param record the <tt>HistoryRecord</tt> to add
   */
  void addHistoryRecord(HistoryRecord record) {
    historyRecords.add(record);

    fireQueryEvent(record);
  }
 /**
  * Adds the given <tt>HistoryQueryListener</tt> to the list of listeners interested in query
  * result changes.
  *
  * @param l the <tt>HistoryQueryListener</tt> to add
  */
 public void addHistoryRecordsListener(HistoryQueryListener l) {
   synchronized (queryListeners) {
     queryListeners.add(l);
   }
 }