Keycloak authentication with extended keycloak-installed adapter

## SimpleDesktopApp.java
package demo;

import java.util.Locale;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import org.keycloak.adapters.installed.KeycloakInstalled;
import org.keycloak.representations.AccessToken;

public class SimpleDesktopApp {

	public static void main(String[] args) throws Exception {

		int timeoutSeconds = 20;

		KeycloakInstalled keycloak = new KeycloakInstalled();
		keycloak.setLocale(Locale.GERMAN);
		keycloak.setHttpResponseWriter((pw, kc) -> {

			pw.println("HTTP/1.1 200 OK");
			pw.println();

			switch (kc.getLoginStatus()) {
			case LOGGED_IN:
				pw.println("<html><h1>Login complete.</h1>"
						+ "<div>Please <a href=\"#\" onclick=\"close_window();return false;\">close</a> this browser tab.</div></html>");
				break;
			case LOGGED_OUT:
				pw.println("<html><h1>Logout complete.</h1>"
						+ "<div>Please <a href=\"#\" onclick=\"close_window();return false;\">close</a> this browser tab.</div></html>");
				break;
			default:
				// ignore
			}
		});

		keycloak.loginDesktop();

		AccessToken token = keycloak.getToken();
		Executors.newSingleThreadExecutor().submit(() -> {

			System.out.println("Logged in...");
			System.out.println("Token: " + token.getSubject());
			System.out.println("Username: " + token.getPreferredUsername());
			try {
				System.out.println("AccessToken: " + keycloak.getTokenString());
			} catch (Exception ex) {
				ex.printStackTrace();
			}

			System.out.printf("Logging out in...%d Seconds%n", timeoutSeconds);
			try {
				TimeUnit.SECONDS.sleep(timeoutSeconds);
			} catch (Exception e) {
				e.printStackTrace();
			}

			try {
				keycloak.logout();
			} catch (Exception e) {
				e.printStackTrace();
			}

			System.out.println("Exiting...");
			System.exit(0);
		});
	}
}