code: protected boolean isSwitchingToNonHttp1Protocol(HttpResponse msg) {
          if (msg.status().code() != HttpResponseStatus.SWITCHING_PROTOCOLS.code()) {
              return false;
          }
          String newProtocol = msg.headers().get(HttpHeaderNames.UPGRADE);
          return newProtocol == null ||
                  !newProtocol.contains(HttpVersion.HTTP_1_0.text()) &&
                  !newProtocol.contains(HttpVersion.HTTP_1_1.text());
      }
docs: Returns true if the server switched to a different protocol than HTTP/1.0 or HTTP/1.1, e.g. HTTP/2 or Websocket.
  Returns false if the upgrade happened in a different layer, e.g. upgrade from HTTP/1.1 to HTTP/1.1 over TLS.