Symfony2允许空路由参数“必须匹配^ / ++（给定）以生成相应的URL”

how can I allow empty route parameters?

If name is an empty, its throws the error Parameter "name" for route "article_test" must match "[^/]++" ("" given) to generate a corresponding URL.

My Controller:

/**
 * @param \AppBundle\Entity\Aritcle $article
 * @param string $name
 * @param string $orderNumber
 * @Route("/{id}/test/{name}/{orderNumber}", name="article_test",
 *     defaults={"name"=null, "orderNumber"=null})
 * @return \Symfony\Component\HttpFoundation\RedirectResponse
 */
public function testAction(Aritcle $article, $name = '', $orderNumber = '') 

thanks