Java Accordion .setExpandedPane (TitledPane value)

public final void setExpandedPane(TitledPane value)

import javafx.application.Application;
import javafx.collections.ObservableList;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Accordion;
import javafx.scene.control.Button;
import javafx.scene.control.TitledPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
//from  w  ww  . jav a 2 s  .  c  o m
public class Main extends Application {
  public static void main(String[] args) {
    Application.launch(args);
  }

  @Override
  public void start(Stage primaryStage) {
    primaryStage.setTitle("Text Fonts");

    Group g = new Group();
    Scene scene = new Scene(g, 550, 250, Color.web("0x0000FF", 1.0));

    TitledPane t1 = new TitledPane("T1", new Button("B1"));
    TitledPane t2 = new TitledPane("T2", new Button("B2"));
    TitledPane t3 = new TitledPane("T3", new Button("B3"));
    Accordion accordion = new Accordion();
    accordion.getPanes().addAll(t1, t2, t3);

    accordion.setExpandedPane(t1);
    
    g.getChildren().add(accordion);

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