Execute bootstrap.php.
$ php bootstrap.php
A listener subscribes to an event via SubscribeTo attribute.
EventAttributePresenter resolves SubscribeTo attribute and realize subscription of autoloaded listeners.
In this case DomainWithEventsController used to be a listener and automatically subscribes to InitApplicationEvent after initiation.
League\Event framework manages subscriptions and event dispatching.
EventDispatcherApplicationProcessor uses League\Event framework to dispatch events and execute controllers.