user/user.go
func LoginURLFederated(c context.Context, dest, identity string) (string, error) {
	req := &pb.CreateLoginURLRequest{
		DestinationUrl: proto.String(dest),
	}
	if identity != "" {
		req.FederatedIdentity = proto.String(identity)
	}
	res := &pb.CreateLoginURLResponse{}
	if err := internal.Call(c, "user", "CreateLoginURL", req, res); err != nil {
		return "", err
	}
	return *res.LoginUrl, nil
}
func LoginURLFederated(c context.Context, dest, identity string) (string, error) {
	req := &pb.CreateLoginURLRequest{
		DestinationUrl: proto.String(dest),
	}
	if identity != "" {
		req.FederatedIdentity = proto.String(identity)
	}
	res := &pb.CreateLoginURLResponse{}
	if err := internal.Call(c, "user", "CreateLoginURL", req, res); err != nil {
		return "", err
	}
	return *res.LoginUrl, nil
}
// LoginURLFederated is like LoginURL but accepts a user's OpenID identifier.