public function getAdapterFactoryClass()
    {
        $config = config('jwt');
        if (!isset($config['adapter'])) {
            $config['adapter'] = 'lcobucci';
        }
        if (class_exists($config['adapter'])) {
            $factoryClass = $config['adapter'];
        } else {
            $factoryClass = 'Canis\Lumen\Jwt\Adapters\\' . ucfirst($config['adapter']) . '\Factory';
            if (!class_exists($factoryClass)) {
                throw new InvalidAdapterException("{$config['adapter']} is not available");
            }
        }
        return $factoryClass;
    }