Undertow Hello World

HelloServer.java

import io.undertow.Undertow;
import io.undertow.util.Headers;

public class HelloServer {
    public static void main(final String[] args) {
        Undertow server = Undertow.builder()
                .addHttpListener(8081, "localhost")
                .setHandler((exchange) -> {
                    exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, "text/plain");
                    exchange.getResponseSender().send("Hello World");
                }).build();

        System.out.println("Server listening on http://localhost:8081");
        server.start();
    }
}