Can't exit out of full screen in my JavaFX application

I was trying to learn javafx. In my application, I decided to check a few things so I decided that you could exit fullscreen only when you typed "abcd". But I can't get it work. I've tried all possible combinations but still can't exit the fullscreen.

package org.example.first;

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.input.KeyCombination;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

import java.io.IOException;

public class HelloApplication extends Application {
    @Override
    public void start(Stage stage) throws IOException {
        Group root = new Group();
        Scene scene = new Scene(root, Color.BLACK);

        Image icon = new Image("file.png");

        stage.setTitle("MyApplication");
        stage.setScene(scene);
        stage.getIcons().add(icon);

        stage.setFullScreen(true);
        stage.setFullScreenExitHint("To exit fullscreen, write abcd");
        stage.setFullScreenExitKeyCombination(KeyCombination.valueOf("abcd"));
        stage.show();
    }

    public static void main(String[] args) {
        launch();
    }
}

This is the code I've written. I've tried to get it to work but I don't know what's wrong with it. JavaFX 17 and Java 18

This is not possible with a key combination like "abcd".

From the documentation of KeyCombination:

A key combination consists of a main key and a set of modifier keys. The main key can be specified by its key code - KeyCodeCombination or key character - KeyCharacterCombination. A modifier key is shift, control, alt, meta or shortcut and can be defined as DOWN, UP or ANY.

"a", "b", "c" and "d" are all main keys which violates that a main key restriction.