protected function getNewUploadModel($id = null)
    {
        $uploadModel = $this->modelName();

        $upload = new $uploadModel;

        if ( ! $upload instanceof Uploadable)
        {
            throw new RuntimeException('The upload model must implement the "Kenarkose\Transit\Contract\Uploadable" interface.');
        }

        if ($id)
        {
            $upload->setKey($id);
        }

        return $upload;
    }