static void finish(TracingFilter filter,
    DubboRequest request, @Nullable Result result, @Nullable Throwable error, Span span) {
    if (request instanceof RpcClientRequest) {
      filter.clientHandler.handleReceive(
        new DubboClientResponse((DubboClientRequest) request, result, error), span);
    } else {
      filter.serverHandler.handleSend(
        new DubboServerResponse((DubboServerRequest) request, result, error), span);
    }
  }
@Test void finish_null_result_and_error_DubboServerRequest() {
    Span span = tracing.tracer().nextSpan().kind(SERVER).start();

    FinishSpan.finish(filter, serverRequest, null, null, span);

    testSpanHandler.takeRemoteSpan(SERVER);
  }