Consider generics on ApplicationListener `@Bean` methods

[philwebb]

See spring-projects/spring-boot#17291 for background.

Currently using this pattern to define an ApplicationListener:

@Bean
public ApplicationListener<ClassPathChangedEvent>  someListener() {
    // ...
}

Will result in a lot of cast class exception because the listener is called for every event. It would be nice if we could consider the generic signature of the bean method and only call listeners that match it.

[sdeleuze]

Linked to #21411?

[philwebb]

No so much since these are actual @Bean methods. Probably somewhat related to #23056 and the general problem of determining type details from a bean definition.

[odrotbohm]

#15303 looks like a duplicate of this.

[sdeleuze]

@odrotbohm Good point, that's the one I was trying to find.