private static function getAnnotationReader()
    {
        if (null === self::$annotationReader) {
            if (!\class_exists('\\Doctrine\\Common\\Annotations\\AnnotationReader') ||
                !\class_exists('\\Doctrine\\Common\\Annotations\\AnnotationRegistry')) {
                throw new \Exception('In order to use graphql annotation, you need to require doctrine annotations');
            }

            AnnotationRegistry::registerLoader('class_exists');
            self::$annotationReader = new AnnotationReader();
        }

        return self::$annotationReader;
    }