message: Check for empty knob in client and server
  Summary: ^
diff: @@ -581,6 +581,7 @@ QuicServerTransport::getPeerCertificate() const {
  }
  void QuicServerTransport::onTransportKnobs(Buf knobBlob) {
  + if (knobBlob->length() > 0) {
  std::string serializedKnobs = std::string(
  reinterpret_cast<const char*>(knobBlob->data()), knobBlob->length());
  VLOG(4) << "Received transport knobs: " << serializedKnobs;
  @@ -589,6 +590,7 @@ void QuicServerTransport::onTransportKnobs(Buf knobBlob) {
  handleTransportKnobParams(*params);
  }
  }
  +}
  void QuicServerTransport::registerAllTransportKnobParamHandlers() {
  registerTransportKnobParamHandler(
  