My game talks to a Java web service that manages some game features like clans.  I want that java service to be able to trigger events in gamesparks that might modify some gamesparks game state or possibly even send a gamesparks message to a player (like you have been invited to join a clan).  Is there a REST API for logging events? Or must I use the callback API feature documented at https://docs.gamesparks.net/howtos/cloud-code-scripting/how-to-implement-external-http-callbacks?