Random menu back bean- primefaces version.

RandomMenu2.java

@ManagedBean
@ViewScoped
public class RandomMenu2 {
    
    private MenuModel<Category> menuModel;
    private Category currentCategory = new Category();
    
    public RandomMenu2() {
        menuModel = new MenuModel<>();
        menuModel.setContents(currentCategory.getChildCategories());
        MenuClickListener menuListener = new MenuClickListener();
        menuModel.addSubscriber(menuListener);
    }
    
    private class MenuClickListener implements Subscriber<Category> {

        @Override
        public void update(Category change) {
            currentCategory = change;
            menuModel.setContents(currentCategory.getChildCategories());
        }
    }
    
    public MenuModel<Category> getMenuModel() {
        return menuModel;
    }

    public Category getCurrentCategory() {
        return currentCategory;
    }
}