Required URL/route parameter set to null when using BeforeEnterEvent.forwardTo()

[eberleant]

Description of the bug

In a BeforeEnterEvent, forwarding to another view with a URL/route parameter (in the path) and query parameters results in the route parameter being set to null. This happens even if the route parameter is required.

Expected behavior

The route parameter should be set to whatever is indicated by the location/path that's being forwarded to.

Minimal reproducible example

View 1:

@Route("")
public class MainView extends VerticalLayout implements BeforeEnterObserver {
    @Override
    public void beforeEnter(BeforeEnterEvent event) {
        event.forwardTo("second/foo", QueryParameters.empty());
    }
}

View 2:

@Route("second")
public class SecondView extends VerticalLayout implements HasUrlParameter<String> {
    @Override
    public void setParameter(BeforeEvent event, String parameter) {
        add("URL Parameter Value: " + parameter);
    }
}

After going to View 1, you should be forwarded to View 2 with route parameter "foo". However, the route parameter is null. This is also reproducible using BeforeEnterEvent.rerouteTo() (instead of forwardTo()).

If you remove QueryParameters.empty() from the call to forwardTo(), it works as expected.

Example project: missing-url-param.zip

Versions

• Vaadin / Flow version: 24.4.8, 24.4.13 (haven't tested other versions)
• Java version: 17
• OS version: N/A
• Browser version (if applicable): Tested on Chrome, Firefox, and Safari
• Application Server (if applicable): Jetty 11, 12
• IDE (if applicable): N/A

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.5.0.rc2 and is also targeting the upcoming stable 24.5.0 version.