public void AddInputSource <T>(int id, CachedEventInputSource <T> controller) where T : InputEvent
 {
     PerInputEventType <T> .mappingById.Add(id, controller);
 }
 public void AddInputSource <T>(string id, CachedEventInputSource <T> controller) where T : InputEvent
 {
     AddInputSource(id.GetHashCode(), controller);
 }