@Override
  public void run() {
    LogConfigurator.setLevel("", "OFF");
    // presume ethereum mainnet for reference and state tests
    SignatureAlgorithmFactory.setDefaultInstance();
    Vertx.vertx()
        .createHttpServer(
            new HttpServerOptions()
                .setHost(host)
                .setPort(port)
                .setHandle100ContinueAutomatically(true)
                .setCompressionSupported(true))
        .requestHandler(req -> req.bodyHandler(body -> handle(req, body)))
        .listen()
        .onSuccess(
            server -> System.out.println("Transition server listening on " + server.actualPort()))
        .onFailure(
            err -> System.err.println("Failed to start transition server: " + err.getMessage()));
  }
Default constructor for the T8nServerSubCommand class. This constructor is required by PicoCLI
and assigns null to parentCommand.
ethereum/evmtool/src/main/java/org/hyperledger/besu/evmtool/T8nServerSubCommand.java