protected function setupDropboxHeaders()
    {
        $headers = [
            'Dropbox-API-Arg' => json_encode(
                $this->request
            ),
        ];
        if (!empty($this->content) ||
               $this->apiEndpoint == 'files/upload_session/finish') {
            // The upload_session/finish API requires a Content-Type, always
            $headers['Content-Type'] = 'application/octet-stream';
        }

        return $headers;
    }