SessionFixationProtectionEvent is not published in Spring WebFlux

[dgempiuc]

Describe the bug
with the default configuration, spring security invalidates the existing session when the user authenticates and creates a new one. it is sensible to prevent session fixation attack.

SessionFixationProtectionEvent is not working when I use it in ApplicationListener implementation.

To Reproduce

@Component
public class TestListener implements ApplicationListener<SessionFixationProtectionEvent> {
    @Override
    public void onApplicationEvent(SessionFixationProtectionEvent sessionFixationProtectionEvent) {
        System.out.println("session fixation event");
        System.out.println(sessionFixationProtectionEvent.getOldSessionId());
        System.out.println(sessionFixationProtectionEvent.getNewSessionId());
    }
}

Expected behavior
there is no stdout logs in console.

Sample
just create secure webflux project. for example, /hello api.

/hello (session-id=x)
/login (redirected to login,session-id=x)

after successfull authentication, session-id is set to y.

/hello (session-id=y)

[jzheaux]

This appears related to #4961

[rwinch]

This does appear to be a duplicate. I'm closing in favor of gh-4961. @dgempiuc please reopen if you disagree