docs: protected void resetCallbackCursor() throws SIResourceException, SISessionDroppedException
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.entry(tc, "resetCallbackCursor", new Integer(hashCode()));
  
      synchronized(this)
      {
        unlockAllUnread();
  
        callbackEntryMsg = lastMsg;
        currentMsg = lastMsg;
        messageAvailable = false;
        endReached = false;
        validState = false;
      }
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.exit(tc, "resetCallbackCursor", this);
    }