Need help integrating Vaadin into template

Hi,

This small test works without problems when I call it in a browser. When I click on the button I see a POST request to /vaadinServlet/UIDL/?v-uiId=5

@Theme("lei")
@Widgetset("com.eqs.lei.LeiWidgetset")
@SpringUI(path="/foo")
public class Foo extends UI {
    @Override
    protected void init(VaadinRequest vaadinRequest) {
        final VerticalLayout layout = new VerticalLayout();
        setContent(layout);
        Button button = new Button();
        layout.addComponent(button);
        button.addClickListener(e -> {
            layout.addComponent(new Label("OK"));
        });
    }
}

My spring boot application uses a ThymeLeaf include template which generates the following integration code:

<div>
<div id="vaadin-1" class="v-app lei">
    <div class="v-app-loading"></div>
    <noscript>
        You have to enable javascript in your browser to use an application built with Vaadin.
    </noscript>
</div>
<script type="text/javascript" src="/VAADIN/vaadinBootstrap.js?v=7.7.3"></script>
<script type="text/javascript">//<![CDATA[
    vaadin.initApplication("vaadin-1", {
        "theme": "lei",
        "versionInfo": {
            "vaadinVersion": "7.7.3"
        },
        "widgetset": "com.eqs.lei.LeiWidgetset",
        "comErrMsg": {
            "caption": "Communication problem",
            "message": "Take note of any unsaved data, and <u>click here</u> or press ESC to continue.",
            "url": null
        },
        "authErrMsg": {
            "caption": "Authentication problem",
            "message": "Take note of any unsaved data, and <u>click here</u> or press ESC to continue.",
            "url": null
        },
        "sessExpMsg": {
            "caption": "Session Expired",
            "message": "Take note of any unsaved data, and <u>click here</u> or press ESC key to continue.",
            "url": null
        },
        "vaadinDir": "/VAADIN/",
        "debug": true,
        "standalone": false,
        "heartbeatInterval": 300,
        "browserDetailsUrl": "/foo",
        "serviceUrl": "/foo"
    });
//]]></script>
</div>

When I click on the button now I see a request to /foo/UIDL/?v-uiId=5, resulting in a 404 error and displaying "Server connection lost, trying to reconnect...". Please help!

Thanks,
Roland

Found this solution:
        "serviceUrl": "/vaadinServlet"