Symfony\Component\HttpFoundation\Response::isSuccessful PHP Method

    public function isSuccessful()
    {
        return $this->statusCode >= 200 && $this->statusCode < 300;
    }

    /**
     * 
     *
     * @param Event $event An Event instance
     */
    public function filter(Event $event, Response $response)
    {
        if (!$configuration = $event->get('request')->attributes->get('_cache')) {
            return $response;
        }

        if (!$response->isSuccessful()) {
            return $response;
        }

        if (null !== $configuration->getSMaxAge()) {
            $response->setSharedMaxAge($configuration->getSMaxAge());
        }

        if (null !== $configuration->getMaxAge()) {
            $response->setMaxAge($configuration->getMaxAge());
        }

        if (null !== $configuration->getExpires()) {
            $date = \DateTime::create(\DateTime::createFromFormat('U', $configuration->getExpires(), new \DateTimeZone('UTC')));

            $response->setLastModified($date);
        }

        return $response;
    }