if (transport != null) transport.passDown(new Event(Event.MSG, msg));
    public void add(long seqno, Message msg) {        Long tmp=new Long(seqno);        synchronized(msgs) {  // the contains() and put() should be atomic            if(!msgs.containsKey(tmp))                msgs.put(tmp, msg);        }        if (transport != null)            transport.passDown(new Event(Event.MSG, msg));        retransmitter.add(seqno, seqno);    }