Jetty 12: inject business object into Server Endpoint without annotations

Question

I have a little application that has a @ServerEndpoint defined (for websockets). Now i would like to inject a business object that does some logic, so i can work with that.

Here i create the jetty server and tell him to use my EventSocket.class which contains the @ServerEndpoint("/").

public JettyServer(Application application) {
        this.application = application;
        this.server = new Server(8080);
        EventSocket.application = application; //so nasty, need to figure out how to inject correctly in constructor

        ServletContextHandler servletContextHandler = new ServletContextHandler(ServletContextHandler.SESSIONS);
        servletContextHandler.setContextPath("/");
        server.setHandler(servletContextHandler);

        // Add jakarta.websocket support
        JakartaWebSocketServletContainerInitializer.configure(servletContextHandler, (context, container) ->
        {
            container.addEndpoint(EventSocket.class);
        });

        // Add default servlet (to serve the html/css/js)
        // Figure out where the static files are stored.
        URL urlStatics = Thread.currentThread().getContextClassLoader().getResource("index.html");
        Objects.requireNonNull(urlStatics, "Unable to find index.html in classpath");
        String urlBase = urlStatics.toExternalForm().replaceFirst("/[^/]*$", "/");
        ServletHolder defHolder = new ServletHolder("default", new DefaultServlet());
        defHolder.setInitParameter("resourceBase", urlBase);
        defHolder.setInitParameter("dirAllowed", "true");
        servletContextHandler.addServlet(defHolder, "/");
    }

Each time a request comes in, jetty creates a new instance of this EventSocket object. Now i need to somehow modify jetty that it uses a special configuration when it wants to create that object, because i need to define a listener in this EventSocket.java.

The part where i need this listener in EventSocket:

@OnMessage
    public void onMessage(String message) {
        System.out.println(message);
        String command = message.split(":")[0];
        switch (command) {
            case "x": listener.gotCalledWith(message); break;
        }

listener is not defined, it should be passed to the default constructor of EventSocket, but thats not possible because i have no clue how to configure jetty to use another constructor. I already created https://github.com/jetty/jetty.project/issues/11502 but no answer yet. Any hint/idea is appreciated!