Method aliases should be created at compile time (but only as needed) using the same rules that JRuby follows.
import com.google.appengine.api.users.UserServiceFactory
@is_admin = UserServiceFactory.getUserService.isUserAdmin
should also be available as...
import com.google.appengine.api.users.UserServiceFactory
@is_admin = UserServiceFactory.get_user_service.is_user_admin