Newscoop\GimmeBundle\EventListener\AllowOriginListener::onKernelRequest PHP Method

    public function onKernelRequest(GetResponseEvent $event)
    {
        $request = $event->getRequest();
        $response = new Response();
        if ($request->getMethod() == 'OPTIONS') {
            $response->headers->set('Access-Control-Allow-Headers', $request->headers->get('Access-Control-Request-Headers'));
            $event->setResponse($response);
        }
    }