求助：Verify Alipay Response Sign Failed

[yanghaitao3864]

请求支付时验签方法中的sign为空值，返回了这个错误：Verify Alipay Response Sign Failed
protected function verifySign(Rocket $rocket): void
{
$response = $rocket->getDestination();
$result = $response->get($this->getResultKey($rocket->getPayload()));
$sign = $response->get('sign', '');
write_log('$sign',$sign);
write_log('$sign',$result);
if ('' === $sign || is_null($result)) {
throw new InvalidResponseException(Exception::INVALID_RESPONSE_SIGN, 'Verify Alipay Response Sign Failed', $response);
}

    verify_alipay_sign($rocket->getParams(), json_encode($result, JSON_UNESCAPED_UNICODE), base64_decode($sign));
}

[yansongda]

可以看下 $response 是啥？