code: public void fsync(Result<Boolean> result)
        throws IOException
    {
      SegmentStream nodeStream = _nodeStream;
        
      // FlushCompletion cont = new FlushCompletion(result, nodeStream, blobStream);
      
      if (nodeStream != null) {
        nodeStream.fsync(result);
      }
      else {
        result.ok(true);
      }
    }
docs: sync the output stream with the filesystem when possible.