code: @Override
    protected Envelope convertRequest(HttpRequest httpRequest) throws RequestConversionException {
      if (!(httpRequest instanceof HttpContent)) {
        throw new RequestConversionException(httpRequest);
      }
  
      HttpContent content = (HttpContent) httpRequest;
      try {
        return Envelope.PARSER.parseFrom(ByteBufUtil.getBytes(content.content()));
      } catch (InvalidProtocolBufferException ipbe) {
        throw new RequestConversionException(httpRequest, ipbe);
      }
    }
docs: {@inheritDoc}