KnpMenuBundle - current class on all subpages

Question

I create a menu by KnpMenuBundle

class Builder extends ContainerAware
{
    public function adminMenu(FactoryInterface $factory, array $options)
    {
        $menu = $factory->createItem('root');

        $menu->addChild('Object', array(
            'route' => 'object',
            'uri' => '/object',
        ));

        return $menu;
    }
}

And when i am on page with url mypage.url/object, all is well - the li element in menu has a current class.

But when I go on the another url, e.g. mypage.url/object/new, then the li element in menu, with uri '/object' hasn't current class.

How can I do that element with uri: '/object', will have a current class and will be active, even the current page (route) is "under uri" /object. (e.g. mypage.url/object/new, mypager.url/object/12/delete, etc.)?