lib/plugins/aws/provider/awsProvider.js/AwsProvider/getAccountInfo
class AwsProvider:  getAccountInfo() {
    return this.request('STS', 'getCallerIdentity', {})
      .then((result) => {
        const arn = result.Arn;
        const accountId = result.Account;
        const partition = _.nth(_.split(arn, ':'), 1); // ex: arn:aws:iam:acctId:user/xyz
        return {
          accountId,
          partition,
          arn: result.Arn,
          userId: result.UserId,
        };
      });
  }