使用域范围委派的gmail users.watch API 400错误请求

Question

呼叫用户时收到400错误请求。通过GCP Cloud Function观看Gmail API

我正在尝试自动对用户GSuite电子邮件帐户进行watch（）调用。我已经按照以下链接中概述的步骤授予了域范围内对Cloud Function的默认服务帐户的访问权限

https://developers.google.com/admin-sdk/reports/v1/guids/delegation

我已授权以下范围： profile,email, https://mail.google.com/,https://www.googleapis.com/auth/gmail.metadata, https://www.googleapis.com/auth/gmail.modify, https://www.googleapis.com/auth/gmail.readonly

已部署的云功能代码：

exports.watchEmail = async () => {
  console.info('authenticating');

  const auth = await google.auth.getClient({
    scopes: ['profile',
      'email',
      'https://mail.google.com/',
      'https://www.googleapis.com/auth/gmail.metadata',
      'https://www.googleapis.com/auth/gmail.modify',
      'https://www.googleapis.com/auth/gmail.readonly'],
  });

  console.info('<-- authenticated');

  console.info('watch on email', 'no-reply@telico.ca');
  const api = google.gmail({ version: 'v1', auth });
  const response = await api.users.watch({
    userId: '<USER_EMAIL>',
    requestBody: {
      topicName: 'projects/<PROJECT_ID>/topics/processEmail',
      labelIds: ["INBOX"]
    }
  });
  console.info('<-- watch on file', JSON.stringify(response));
};

执行CloudFunction时，我看到Error: Bad Request at Gaxios.request打印在日志中。