Run code:

    @Override
    public void start(Stage stage) throws Exception {
        Accordion acc = new Accordion();

        TitledPane pane1 = new TitledPane("Some text", new Label("Node"));
// pane1.setText("Some text");
// pane1.setGraphic(new Label("Node"));
        pane1.setContent(new Button("Some button"));
        acc.getPanes().addAll(pane1);

        VBox pane = new VBox();
        pane.getChildren().addAll(acc);
        Scene scene = new Scene(pane, 300, 700);
        stage.setScene(scene);
        stage.show();
    }

Commented lines of code and constructor has the same result, but constructor doesn't work. Label("Node") is not applied.