/** * getExchangeToken - Returns an exchange token string which can be sent * back to clients and exchanged for a device-linked access token. * * @param string|null $appId * @param string|null $appSecret * * @return string */ public function getExchangeToken($appId = null, $appSecret = null) { return AccessToken::getCodeFromAccessToken($this->accessToken, $appId, $appSecret); }