code: public synchronized void unlockAll()
     {
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "unlockAll");
        if (trackBytes)                                             // f191114
           ++currentBatchNumber;
        if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) SibTr.debug(this, tc, "Current batch number is: " + currentBatchNumber);
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "unlockAll");
     }
docs: This method is called on the queue when an unlockAll() is taking place. This signals that any
  future messages will be arriving with an incremented message batch number and as such we
  should ignore any old messages.
  <p>
  At this point the queue should have been emptied by calling the purge() method to ensure that
  the queue is cleared of unlocked messages.
  
  @see Queue#unlockAll()