I am getting this error: "Self HTTP test not OK!"

while calling

await letsEncrypt.startSecureServer()

having this simple server:

import 'dart:io';
import 'dart:async' show runZonedGuarded;
import 'package:path/path.dart' show join, dirname;

import 'package:shelf/shelf.dart';
import 'package:shelf/shelf_io.dart';
import 'package:shelf_router/shelf_router.dart';
import 'package:shelf_gzip/shelf_gzip.dart';
import 'package:shelf_static/shelf_static.dart';
import 'package:shelf_letsencrypt/shelf_letsencrypt.dart';

Response _echoHandler(Request request) {
  final message = request.params['message'];
  return Response.ok('$message\n');
}

void main(List<String> args) async {
  final ip = InternetAddress.anyIPv4;

  final pathToBuild = join(dirname(Platform.script.toFilePath()), '../../../',
      'mtg.studio.project/ui/build/web');
  final staticHandler =
      createStaticHandler(pathToBuild, defaultDocument: 'index.html');

  // Configure routes.
  final app = Router();
  app.get('/sample/route/<message>', _echoHandler);    

  runZonedGuarded(() async {
    final handlers = Pipeline()
        .addMiddleware(logRequests())
        .addMiddleware(gzipMiddleware)
        .addHandler(Cascade().add(staticHandler).add(app).handler);

    // For running in containers, we respect the PORT environment variable.
    final port = int.parse(Platform.environment['PORT'] ?? '3030');
    final domain = 'domain.com';
    final domainEmail = '[email protected]';
    final certificatesDirectory = '.'; // /etc/letsencrypt/live';

    // The Certificate handler, storing at `certificatesDirectory`.
    final certificatesHandler =
        CertificatesHandlerIO(Directory(certificatesDirectory));

    // The Let's Encrypt integration tool in `staging` mode:
    final LetsEncrypt letsEncrypt =
        LetsEncrypt(certificatesHandler, production: false);

    // final server = await serve(handlers, ip, port);
    final servers = await letsEncrypt.startSecureServer(
      handlers,
      domain,
      domainEmail,
      port: port,
      securePort: 3443,
    );

    var server = servers[0]; // HTTP Server.
    var serverSecure = servers[1]; // HTTPS Server.

    // Enable gzip:
    server.autoCompress = true;
    serverSecure.autoCompress = true;
    print('☀️Serving at http://${server.address.host}:${server.port}');
    print(
        '☀️Serving at https://${serverSecure.address.host}:${serverSecure.port}');
  }, (e, stackTrace) => print('🐞Server error: $e $stackTrace'));
}

I'd like to have a server that listens on port 443 for multiple domains, resolves the certificates separately, and routes the requests in a per-domain basis. Is this supported / planned? Any thoughts on how I contribute to this package (what design decisions would you prefer)?