Quiero desarrollar una aplicación que utilice controlesfx Notificaciones para mostrar algunas notificaciones en el modo de bandeja del sistema. En modo normal, mi aplicación funciona bien y la notificación se puede mostrar con éxito. Pero cuando oculto el escenario en la bandeja del sistema, se produce NullPointerException. No sé cómo puedo solucionar este problema.

import java.awt.AWTException;
import java.awt.MenuItem;
import java.awt.PopupMenu;
import java.awt.SystemTray;
import java.awt.Toolkit;
import java.awt.TrayIcon;
import java.awt.event.ActionListener;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.EventHandler;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javafx.stage.WindowEvent;


public class TryIconNotification extends Application {
           private boolean firstTime;
private TrayIcon trayIcon;
@Override
public void start(Stage stage) throws Exception {
    firstTime = true;
    Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));

    Scene scene = new Scene(root);

     createTrayIcon(stage);
    firstTime = true;
    Platform.setImplicitExit(false);


    stage.setScene(scene);
    stage.show();
}


    public void createTrayIcon(final Stage stage) {
    if (SystemTray.isSupported()) {
        // get the SystemTray instance
        SystemTray tray = SystemTray.getSystemTray();
        // load an image
        java.awt.Image image = null;
        image = Toolkit.getDefaultToolkit().getImage("icons\\iconify.png");

        stage.setOnCloseRequest(new EventHandler<WindowEvent>() {
            @Override
            public void handle(WindowEvent t) {
                hide(stage);
            }
        });

        // create a action listener to listen for default action executed on the tray icon
        final ActionListener closeListener = new ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent e) {
                stage.hide();

            }
        };

        ActionListener showListener = new ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent e) {
                Platform.runLater(new Runnable() {
                    @Override
                    public void run() {
                        stage.show();
                    }
                });
            }
        };
        // create a popup menu
        PopupMenu popup = new PopupMenu();

        MenuItem showItem = new MenuItem("Open app");

        showItem.addActionListener(showListener);
        popup.add(showItem);

        MenuItem closeItem = new MenuItem("Exit");
        closeItem.addActionListener(closeListener);
        popup.add(closeItem);
        /// ... add other items
        // construct a TrayIcon
        trayIcon = new TrayIcon(image, "Systray", popup);
        // set the TrayIcon properties
        trayIcon.addActionListener(showListener);
        // ...
        // add the tray image
        try {
            tray.add(trayIcon);
        } catch (AWTException e) {
            System.err.println(e);
        }
        // ...
    }
}
    public void showProgramIsMinimizedMsg() {
    //only in first time show the message
    if (firstTime) {
        trayIcon.displayMessage("System Tray",
                "Iconified",
                TrayIcon.MessageType.INFO);
        firstTime = false;
    }
}

        private void hide(final Stage stage) {
    Platform.runLater(new Runnable() {
        @Override
        public void run() {
            if (SystemTray.isSupported()) {
                stage.hide();
                showProgramIsMinimizedMsg();
            } else {
                 System.exit(0);
                System.out.println("Not Support Sys Tray");
            }
        }
    });
}
/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    launch(args);
}

}

Y esta es mi clase de controlador:

import java.net.URL;
import java.util.ResourceBundle;
import java.util.Timer;
import java.util.TimerTask;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Label;
import javafx.stage.Stage;
import org.controlsfx.control.Notifications;


public class FXMLDocumentController  implements Initializable   {

@FXML
private Label label;

@FXML
private void handleButtonAction(ActionEvent event) {
    Stage stage = (Stage) label.getScene().getWindow();
    stage.hide();
}

public void createNotification() {

    Notifications.create()
            .text("This is a Notification")
            .title("Notifications")
            .showInformation();
}

@Override
public void initialize(URL url, ResourceBundle rb) {

 Timer timer = new Timer();

    timer.scheduleAtFixedRate(new TimerTask() {

        @Override
        public void run() {
          Platform.runLater(()->createNotification());
        }

    }, 5000, 10000);
}

}