public static function create($mimeType='application/json') {
        $availableSerializers = \ClassInfo::implementorsOf('Ntb\RestAPI\IRestSerializer');
        foreach($availableSerializers as $serializer) {
            /** @var IRestSerializer $instance */
            $instance = new $serializer();
            if($instance->active() && $instance->contentType() === $mimeType) {
                return $instance;
            }
        }
        throw new RestUserException("Requested Accept '$mimeType' not supported", 404);
    }