code: public boolean flushable() throws SIResourceException
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.entry(tc, "flushable");
  
      // Short circuit if we've never created a stream
      if (streamSet == null)
      {
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
          SibTr.exit(tc, "flushable", Boolean.TRUE);
        return true;
      }
  
      StreamSet streamSet = getStreamSet();
  
      //iterate over the non-null streams
      Iterator itr = streamSet.iterator();
      while(itr.hasNext())
      {
        SourceStream stream = (SourceStream) itr.next();
        if(!stream.flushable())
        {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(tc, "flushable", Boolean.FALSE);
          return false;
        }
      }
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(tc, "flushable", Boolean.TRUE);
      return true;
    }
docs: Check whether a particular set of streams is flushable.  A stream is
  flushable if the use count is zero and none of the component
  streams contain a V/U or L/U tick
  
  @return true if the set of streams are all flushable, and false otherwise.