akka.actor.typed.Props of the singleton actor, such as dispatcher settings.
Additional settings, typically loaded from configuration.
Message sent to the singleton to tell it to stop, e.g.
Message sent to the singleton to tell it to stop, e.g. when being migrated. If this is not defined it will be stopped automatically. It can be useful to define a custom stop message if the singleton needs to perform some asynchronous cleanup or interactions before stopping.