Add ApplicationReadyEvent

[snicoll]

Such event may be useful for listeners that requires to perform the operation when the application is ready to use. Would be triggered right before returning the ApplicationContext from the run method.

[philwebb]

I think ApplicationReadyEvent should probably extend SpringApplicationEvent so that it has parity with ApplicationFailedEvent. We've probably also got a package tangle now, so we should trigger it from EventPublishingRunListener.finished() rather than directly from SpringApplication.

[philwebb]

Also, is there a specific use-case where this is needed over a ContextRefreshedEvent?

[snicoll]

In the reference issue. The maven plugin listens to it to let the integration tests run.

I disagree with it extending SpringApplicationEvent. This is what I did initially but semantically it does not fit: when you handle that event, the SpringApplication has been "fully loaded" and any attempt to modify it (call a setter, register a listener) will just not do what you expect. I think the application context is a much better source in that regard.

Good catch for the cycle.

[philwebb]

I think having context of which SpringApplication triggered the event is still useful. We also have precedence with ApplicationPreparedEvent.