code: protected synchronized void notifyObservers (int id, int keyCode, long timestamp)
      {
          _keyOp.init(id, keyCode, timestamp);
          _observers.apply(_keyOp);
      }
docs: Notifies all registered key observers of the supplied key event. This method provides a
  thread-safe manner in which to notify the observers, which is necessary since the
  {@link KeyInfo} objects do various antics from the interval manager thread whilst we may do
  other notification from the AWT thread when normal key events are handled.