if (log.isTraceEnabled()) { log.trace("cancel " + d); }
if (trace) { log.trace("cancel " + d); }
   public void cancel(Delivery d) throws Throwable   {      if (log.isTraceEnabled()) { log.trace("cancel " + d); }            state.cancelDelivery(d);            if (log.isTraceEnabled()) { log.trace(this + " marked message " + d.getReference() + " as undelivered"); }   }