How to specify server to access datastore from Java app?

I'm trying to access Google Datastore from a standalone Java app (not a web application or servlet), using the low-level Java API, running on my local system.

remoteapi appears the simplest way do this. However, I need to specify a server per

RemoteApiOptions options = new RemoteApiOptions()
   .server("your_app_id.appspot.com", 443)    
   .useApplicationDefaultCredential();

How do I specify the server(...) invocation to access Datastore? I have run

gcloud auth login

and I have a project configured for Datastore (with a project ID, etc.) but no 'app_id' since there's no app involved.

Is there a standard server for accessing Datastore? Or is there a better way to access Datastore from a standalone java app?