public function getUploadKey()
    {
        if ( ! empty($this->uploadKey)) {
            return $this->uploadKey;
        }

        $key = $this->getRequest()->header('Upload-Key') ?? Uuid::uuid4()->toString();

        if (empty($key)) {
            return $this->response->send(null, HttpResponse::HTTP_BAD_REQUEST);
        }

        $this->uploadKey = $key;

        return $this->uploadKey;
    }