private void addTree(VerticalLayout layout) {
    TreeData<String> data = new TreeData<>();
    data.addItem(null, "Dad");
    data.addItem("Dad", "Daughter");
    data.addItem("Daughter", "Granddaughter");
    data.addItem("Dad", "Son");
    data.addItem("Daughter", "Grandson");

    Tree<String> tree = new Tree<>("A family", data);
    TreeContextMenu<String> treeContextMenu = new TreeContextMenu<>(tree);
    treeContextMenu.addTreeContextMenuListener(e -> {
        treeContextMenu.removeItems();
        //The path is /resources/images/kitten.jpg
        ClassResource ico = new ClassResource("/images/kitten.jpg");
        treeContextMenu.addItem("Who?",ico, menuItem -> Notification.show(e.getItem()));
    });

    layout.addComponent(tree);
}
 

@Override
public void sourceGenerationExecuted(final Source source, final TestGenerationType generationType, final long testsCreated) {
    UI.getCurrent().access(() -> {
        Item item = resultsTable.getItem(source);
        if (testsCreated == 0 || item == null)
            return;

        String column = (generationType.equals(TestGenerationType.AutoGenerated) ? "Automatic" : "Manual");
        Property<Link> statusProperty = item.getItemProperty(column);
        String fileName;
        if (generationType.equals(TestGenerationType.AutoGenerated)) {
            fileName = CacheUtils.getSourceAutoTestFile(RDFUnitDemoSession.getBaseDir() + "tests/", source);
            statusProperty.setValue(new Link("" + testsCreated, new FileResource(new File(fileName))));
        } else {
            fileName = CacheUtils.getSourceManualTestFile("/org/aksw/rdfunit/tests/", source);
            statusProperty.setValue(new Link("" + testsCreated, new ClassResource(fileName)));
        }
        CommonAccessUtils.pushToClient();
    });

}
 

@Override
public Resource getIconResource(String iconPath) {
    Preconditions.checkNotEmptyString(iconPath, "Icon path should not be empty");

    String icon = iconPath.substring(CLASSPATH_PREFIX.length());
    return new ClassResource(icon);
}
 

private void fillMenu(ContextMenu menu) {
    final MenuItem item = menu.addItem("Checkable \u00d6",
            e -> Notification.show("checked: " + e.isChecked())
    );
    item.setCheckable(true);
    item.setChecked(true);

    MenuItem item2 = menu.addItem("Disabled",new ClassResource("/images/tiger.jpg"),
            e -> Notification.show("disabled")
    );
    item2.setDescription("Disabled item");
    item2.setEnabled(false);

    MenuItem item3 = menu.addItem("Invisible",
            e -> Notification.show("invisible")
    );
    item3.setVisible(false);

    menu.addSeparator();

    //The path is /resources/images/kitten.jpg
    ClassResource ico = new ClassResource("/images/kitten.jpg");
    MenuItem item4 = menu.addItem("Icon + Description + <b>HTML</b>",ico,
            e -> Notification.show("icon")
    );
    item4.setDescription("Test tooltip");
    but3.addClickListener(e -> item4.setDescription(""));
    MenuItem item5 = menu.addItem("Custom stylename",
            e -> Notification.show("stylename")
    );
    //The path is /webapp/VAADIN/themes/contextmenu/images
    ThemeResource resource = new ThemeResource("images/cat.jpg");
    item5.setIcon(resource);

    item5.setStyleName("teststyle");

    MenuItem item6 = menu.addItem("Submenu");
    item6.addItem("Subitem", VaadinIcons.OPTION, e -> Notification.show("SubItem"));
    item6.addSeparator();
    item6.addItem("Subitem",new ThemeResource("images/cat2.jpg"), e -> Notification.show("SubItem"))
            .setDescription("Test");
    MenuItem openWindowNotification = item6.addItem(
            "Open Window + Notification",
            e -> Notification.show("Open Vaadin.com"));
    new BrowserWindowOpener("https://vaadin.com").extend(openWindowNotification);

    MenuItem openWindowDummy = item6.addItem("Open Google");
    new BrowserWindowOpener("https://google.com").extend(openWindowDummy);

    new BrowserWindowOpener("https://yahoo.com")
            .extend(item6.addItem("SubMenu2").addItem("Yahoo!"));
}