boolean memory = super.remove(ref); if (!memory)
synchronized (ref)
   public boolean remove(MessageReference ref) throws Throwable   {      boolean memory = super.remove(ref);      if (!memory)      {         return false;      }      if (ref.isReliable())      {         boolean database = pm.remove(channelID, ref);         if (database && log.isTraceEnabled()) { log.trace("removed " + ref + " from database"); }         return database;      }      return memory;   }