public function jsonSerialize()
    {
        $keyDefinition = \SwaggerValidator\Common\FactorySwagger::KEY_DEFINITIONS;

        $doc                 = json_decode(\SwaggerValidator\Common\Collection::jsonEncode(parent::jsonSerialize()));
        $doc->$keyDefinition = json_decode(\SwaggerValidator\Common\Collection::jsonEncode(\SwaggerValidator\Common\CollectionReference::getInstance()));

        if (count(get_object_vars($doc->$keyDefinition)) < 1) {
            unset($doc->$keyDefinition);
        }

        return $doc;
    }