To reproduce run following code

Expected: "Enter password SecondLine Third line" as prompt

import javafx.application.Application;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.PasswordField;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class PasswordBoxSample extends Application {

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

    private Parent getContent() {

        VBox list = new VBox();
        PasswordField box = new PasswordField();
        box.setPromptText("Enter password\nSecondLine\nThird line");
        
        list.getChildren().addAll(box);
        return list;
    }

    public void start(Stage stage) {
        stage.setX(100);
        stage.setY(100);
        Scene scene = new Scene(getContent());
        stage.setScene(scene);
        stage.show();
    }
}