if (trace) { log.trace("adding callback handler " + callbackHandler); }
log.debug("adding callback handler " + callbackHandler);
   public void addListener(InvokerCallbackHandler callbackHandler)   {                       if (trace) { log.trace("adding callback handler " + callbackHandler); }            if (callbackHandler instanceof ServerInvokerCallbackHandler)      {         ServerInvokerCallbackHandler h = (ServerInvokerCallbackHandler)callbackHandler;         String id = h.getClientSessionId();                   synchronized(callbackHandlers)         {            if (callbackHandlers.containsKey(id))            {               String msg = "The remoting client " + id + " already has a callback handler";               log.error(msg);               throw new RuntimeException(msg);            }            callbackHandlers.put(id, h);         }      }      else      {         throw new RuntimeException("Do not know how to use callback handler " + callbackHandler);      }   }