@Override
 public void afterUpdate(UserReputation rep) {
   if (rep != null) {
     User user = rep.getTargetUser();
     if (user != null) {
       String userKey = user.getKey();
       cache.set(userKey, rep);
     }
   }
 }
 @Override
 public void afterRemove(Long key, UserReputation rep) {
   if (rep != null) {
     User user = rep.getTargetUser();
     if (user != null) {
       String userKey = user.getKey();
       cache.set(userKey, null);
     }
   }
 }