docs: public synchronized boolean isQueueEmpty()
     {
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "isQueueEmpty");
        boolean result = queue.isEmpty();
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "isQueueEmpty", ""+result);
        return result;
     }