go-endpoints oauth2 user always nil

How do you make the api explorer oauth2 work for go-endpoints? (scope https://www.googleapis.com/auth/userinfo.email )

func (gs *GreetingService) Store(r *http.Request, req *Request, resp *Response) error {
    c := appengine.NewContext(r)
    u := user.Current(c)
    if u != nil {c.Infof("Hello, %v\n", u)}
    if u != nil {fmt.Printf("Hello, %v\n", u)}
}

u is always nil, in java I had to add something like this to make it work.

@Api(name = "rest1",
     version = "0",
     scopes = {Id.EMAIL_SCOPE},
     clientIds = {Id.WEB_CLIENT_ID, Id.ANDROID_CLIENT_IDd, Id.ANDROID_CLIENT_IDr, Id.EXPLORER_ID},
     audiences = {Id.ANDROID_AUDIENCE})

How do you make it work for go-endpoints?

EDIT

doh! I found this http://godoc.org/github.com/crhym3/go-endpoints/endpoints#CurrentBearerTokenUser PS what is the API_EXPLORER_CLIENT_ID for golang?

doh2!
http://godoc.org/github.com/crhym3/go-endpoints/endpoints#pkg-constants

func (gs *GreetingService) Store(r *http.Request, req *Request, resp *Response) error {
    c := endpoints.NewContext(r)

    u, err := endpoints.CurrentBearerTokenUser(c, []string{"https://www.googleapis.com/auth/userinfo.email"}, []string{"...apps.googleusercontent.com",endpoints.ApiExplorerClientId})
    if err != nil {return err}

    c.Infof("-------------------")
    if u != nil {c.Infof("Hello, %v\n", u)}
    c.Infof("-------------------")
}