Google app engine: Separating test and production version of cloud endpoints

I made a project on the google app engine, following the multi-class API endpoints tutorial in the official documentation.

I need multiple projects (frontends, mobile, server,..) to be able to make API calls onto these java end points.

This works, but using versions has proven difficult. I tried modifying the version in the appengine-web.xml. Using mvn appengine:update and endpoint generation, I can deploy to the default version on the cloud, but this ignores the version I specified in the xml.

Using appcfg, I can deploy to other versions but then they do not include my endpoints.

Without versions, I would need to use a seperate project for the development/test environment and one for the production environment.

Additionally, I want to use different versions for the data store, but I can't find a lot of information on this. Having a seperate data store for testing and production seems to require making a seperate project.

So is this the normal way to work with test environments? Test and deploy to a seperate project with a test data store? Or is there a way to create a development version and a production version and have their endpoints be seperately callable and make seperate data store calls.

Thanks and good day.