从Google Cloud Endpoint访问UserService

I am developing a Google App Engine app with a Cloud Endpoint. My app uses OpenID to authenticate a user. Once the user has logged in, in the same session, there is a call to the endpoint. In the endpoint code I want to access the user service for the current logged in user. This works on the development server, but after deploy to Google the userService returns null to the getCurrentUser() call.I am developing a Google App Engine app with a