ApiPlatform\Core\EventListener\SerializeListener::serializeRawData PHP Метод

    private function serializeRawData(GetResponseForControllerResultEvent $event, Request $request, $controllerResult)
    {
        if (!$request->attributes->get('_api_respond')) {
            return;
        }
        if (is_object($controllerResult)) {
            $event->setControllerResult($this->serializer->serialize($controllerResult, $request->getRequestFormat()));
            return;
        }
        if (!$this->serializer instanceof EncoderInterface) {
            throw new RuntimeException(sprintf('The serializer instance must implements the "%s" interface.', EncoderInterface::class));
        }
        $event->setControllerResult($this->serializer->encode($controllerResult, $request->getRequestFormat()));
    }