code: public void processFlushQuery(ControlAreYouFlushed flushQuery) throws SIResourceException
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.entry(tc, "processFlushQuery", new Object[] { flushQuery });
  
      SIBUuid12 streamID = flushQuery.getGuaranteedStreamUUID();
  
      try
      {
        //synchronize to give a consistent view of the flushed state
        synchronized(this)
        {
          SIBUuid8 requestor = flushQuery.getGuaranteedSourceMessagingEngineUUID();
          if(isFlushed(streamID))
          {
            // It's flushed.  Send a message saying as much.
            downControl.sendFlushedMessage(requestor, streamID);
          }
          else
          {
            // Not flushed.  Send a message saying as much.
            downControl.sendNotFlushedMessage(requestor, streamID, flushQuery.getRequestID());
          }
        }
      }
      catch (SIResourceException e)
      {
        // FFDC
        FFDCFilter.processException(
          e,
          "com.ibm.ws.sib.processor.gd.SourceStreamManager.processFlushQuery",
          "1:1333:1.102",
          this);
  
        SibTr.exception(tc, e);
  
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
          SibTr.exit(tc, "processFlushQuery", e);
  
        throw e;
      }
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.exit(tc, "processFlushQuery");
  
    }
docs: Handle a flush query.
  
  @param flushQuery The control message which elicited the query.
  @throws SIResourceException I'm pretty sure this can't actually
  be thrown.