if(log.isInfoEnabled()) log.info("passing down GET_DIGEST_STATE");
if(log.isDebugEnabled()) log.debug("passing down GET_DIGEST_STATE");
    void handleStateReq(Object sender, long state_id) {        if(sender == null) {            if(log.isErrorEnabled()) log.error("sender is null !");            return;        }        synchronized(state_requesters) {            if(state_requesters.size() > 0) {  // state transfer is in progress, digest was requested                state_requesters.add(sender);            }            else {                state_requesters.add(sender);                digest=null;                if(log.isInfoEnabled()) log.info("passing down GET_DIGEST_STATE");                passDown(new Event(Event.GET_DIGEST_STATE));            }        }    }