Unable to delete AppEngine Service instance using App Engine Admin API - google-app-engine

Question

I am attempting to programmatically delete an App Engine (Standard) backend instance. The code for deleting it runs as a Servlet on another module/service of the same project.
I am able to list the instance and all the details, but attempting to delete it throws the 403 error.
{
"code" : 403,
"errors" : [ {
"domain" : "global",
"message" : "Request had insufficient authentication scopes.",
"reason" : "forbidden"
} ],
"message" : "Request had insufficient authentication scopes.",
"status" : "PERMISSION_DENIED"
}
I am using the App engine default service account:
AppIdentityCredential credential = new AppIdentityCredential(Arrays.asList(AppengineScopes.APPENGINE_ADMIN));
Appengine engine = new Appengine.Builder(new UrlFetchTransport(), new JacksonFactory(), credential).setApplicationName("AppEngineManager").build();
//list all instances - this works fine
//now delete an instance
engine.apps().services().versions().instances().delete(appId, serviceId, version, <instanceid>).execute()
The default App engine service account has Editor role (I also tried manually adding App Engine Admin role, to no avail)
The service account name printed before running the code is also correct. What could be wrong?

Answer 1

This solved it!
AppIdentityCredential credential = new AppIdentityCredential(Arrays.asList(AppengineScopes.**CLOUD_PLATFORM**));
I was using the more obvious looking AppengineScopes.APPENGINE_ADMIN, but this doesn't work. Wish Google would improve their documentation. Had sleepless nights because of a production issue which required us to delete the instances programmatically to solve it.