public void showMessage(@NlsContexts.NotificationContent String message, MessageType messageType) {
    NotificationGroup group = Optional
      .ofNullable(NotificationGroup.findRegisteredGroup(myNotificationDisplayId))
      .orElseGet(() -> NotificationGroup.balloonGroup(myNotificationDisplayId));
    group.createNotification(message, messageType).notify(null);
  }
public void showMessage(@NlsContexts.NotificationContent String message, MessageType messageType)