Builds the bundle.
It is only ever called once when the cache is empty.
This method can be overridden to register compilation passes, other extensions, ...
ContainerBuilder $container A ContainerBuilder instance:
Overrides Bundle::build
public function build(ContainerBuilder $container) {
$container
->register('url_alter_test.path_subscriber', 'Drupal\\url_alter_test\\PathSubscriber')
->addTag('event_subscriber');
}