static protected function registerAnnotations()
    {
        if (self::$annotationsRegistered === false) {
            AnnotationRegistry::registerFile(__DIR__ . '/../Annotation/ResourceIdentifier.php');
            AnnotationRegistry::registerFile(__DIR__ . '/../Annotation/Relationship.php');
            AnnotationRegistry::registerFile(__DIR__ . '/../Annotation/Attribute.php');
            AnnotationRegistry::registerFile(__DIR__ . '/../Annotation/Link.php');

            self::$annotationsRegistered = true;
        }
    }