identity.go
func ServiceAccount(c context.Context) (string, error) {
	req := &pb.GetServiceAccountNameRequest{}
	res := &pb.GetServiceAccountNameResponse{}

	err := internal.Call(c, "app_identity_service", "GetServiceAccountName", req, res)
	if err != nil {
		return "", err
	}
	return res.GetServiceAccountName(), err
}
func ServiceAccount(c context.Context) (string, error) {
	req := &pb.GetServiceAccountNameRequest{}
	res := &pb.GetServiceAccountNameResponse{}

	err := internal.Call(c, "app_identity_service", "GetServiceAccountName", req, res)
	if err != nil {
		return "", err
	}
	return res.GetServiceAccountName(), err
}
// ServiceAccount returns a string representing the service account name, in
// the form of an email address (typically app_id@appspot.gserviceaccount.com).