Thread.exit () line: unavailable error in javafx swing integration using jfxpanel

I am trying to use fxml inside a swing application. The problem I am facing is the jframe, but the javafx components are not visible. The error is not listed, but after debugging it gives the error "Thread.exist () line: not available". I have complete code here: -

package nonResponsiveButtons;

import java.awt.Color;
import javafx.embed.swing.JFXPanel;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.Pane;
import javafx.application.Platform;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class NonResponsiveButtons extends JFrame {

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

    public NonResponsiveButtons(){

        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                try{
                new JFXPanel();
                BottomPanel bottomPanel = new BottomPanel();
                add(bottomPanel);
                }
                catch(Exception e){
                    System.out.println("Error in swing utilities thread :" + e.getMessage());
                }

            }
        });

        this.setSize(600, 600);
        getContentPane().setLayout(null);
        add(jPanel());      


        setVisible(true);
    }

    private JPanel jPanel(){
        JPanel panel = new JPanel();
        panel.setSize(600,500);
        panel.setBackground(Color.blue);
        return panel;
    }

    private class BottomPanel extends JPanel{
        private JFXPanel jfxPanel;
        private Pane scenePane;
        private Button btn1;
        private Button btn2;
        private Button btn3;

        private BottomPanel(){
            setSize(600, 100);
            setLocation(0, 500);
            setLayout(null);



            Platform.runLater(new Runnable(){
                @Override
                public void run(){
                    getScenePane().getChildren().addAll(getBtn1(),getBtn2(),getBtn3());
                    getjfxPanel().setScene(new Scene(getScenePane()));

                }

            });
        }

        private JFXPanel getjfxPanel(){
            if(jfxPanel == null){
                jfxPanel = new JFXPanel();
                jfxPanel.setSize(600,200);
            }
            return jfxPanel;
        }

        private Pane getScenePane(){
            if(scenePane == null){
                scenePane = new Pane();
                scenePane.setStyle("-fx-background-color:#666666");
            }
            return scenePane;
        }

        /*
         * using getters will avoid :-
         * 1. null pointer exceptions
         * 2. standard coding format
         * 3. makex programming felxible
         */
        private Button getBtn1(){
            if(btn1 == null){
                btn1 = new Button();
                btn1.setPrefSize(100, 50);
                btn1.setLayoutX(80);
            }
            return btn1;
        }
        private Button getBtn2(){
            if(btn2 == null){
                btn2 = new Button();
                btn2.setPrefSize(100, 50);
                btn2.setLayoutX(80);
            }
            return btn2;
        }
        private Button getBtn3(){
            if(btn3 == null){
                btn3 = new Button();
                btn3.setPrefSize(100, 50);
                btn3.setLayoutX(80);
            }
            return btn3;
        }
    }


}