code: public EntityManager createLocalEntityManager(String serviceURL, String projectId) {
      return createLocalEntityManager(serviceURL, projectId, null);
    }
docs: Creates and returns an {@link EntityManager} that allows working with the local Datastore
  (a.k.a Datastore Emulator). Specified project ID will be used.
  
  @param serviceURL
  Service URL for the Datastore Emulator. (e.g. http://localhost:9999)
  @param projectId
  the project ID. The specified project need not exist in Google Cloud.
  @return an {@link EntityManager} that allows working with the local Datastore (a.k.a Datastore
  Emulator).