private void onHeaders(HeadersFrame frame) {
   int streamId = frame.getStreamId();
   IStream stream = streams.get(streamId);
   if (stream == null) {
     RstInfo rstInfo = new RstInfo(streamId, StreamStatus.INVALID_STREAM);
     LOG.debug("Unknown stream, {}", rstInfo);
     rst(rstInfo, new Callback.Adapter());
   } else {
     processHeaders(stream, frame);
   }
 }