code: public void forceFlush(SIBUuid12 streamID) throws SIErrorException
      {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.entry(tc, "forceFlush", streamID);
  
          StreamSet streamSet = streamSets.get(streamID);
          streamSet.dereferenceControlAdapter();
  
          // Send out a flushed message.  If this fails, make sure we get
          // to at least invoke the callback.
          try
          {
              // The Cellule argument is null as it is ignored by our parent handler
              // this flush message should be broadcast downstream.
              // This will also implicitly remove the streamSet
              downControl.sendFlushedMessage(null, streamID);
          } catch (Exception e)
          {
              // FFDC
              FFDCFilter.processException(
                                          e,
                                          "com.ibm.ws.sib.processor.gd.InternalOutputStreamManager.forceFlush",
                                          "1:743:1.48.1.1",
                                          this);
  
              // Note that it doesn't make much sense to throw an exception here since
              // this is a callback from stream array map.
              if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
                  SibTr.exit(tc, "forceFlush", e);
              return;
          }
  
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
              SibTr.exit(tc, "forceFlush");
      }
docs: This method will be called to force flush of streamSet