Apparently there's no straightforward way supported by Google Cloud Endpoints for allowing/limiting access to a private Endpoints API to only your Mobile App (Android or iOS). 1 2 3 4
There likely are many Apps where the developer would like to have her back-end on Google Cloud Platform. And, likely many of these Apps would like to use the backend API without having the App user sign-in to their Google Account.
Is (at least current version) Endpoints meant to be used by only those Mobile Apps where users are Google users or where the APIs are open? Or Am I missing something?