Delayed Restart is not working while using BackoffSupervisor in Akka Classic Actors (Scala)

Question

I'm trying to use BackoffSupervisor to delay the restart. I've given 10.sec as minimum backoff but on Exception it is restarting the actor immediately.

Here is code:

  `object Task2Implementation extends App {
    val system = ActorSystem("system")
    val actor = system.actorOf(BackoffSupervisor.props(BackoffOpts.onStop(
      Props[TestActor],
      "testActor",
      10.seconds,
      30.seconds,
      0.2
    ).withSupervisorStrategy(OneForOneStrategy(){
      case ex:Exception =>
        log.error("Going To Stop!")
        Stop
    })))

    actor ! BadStuff
  }`

Code of TestActor class:

  `class TestActor extends Actor {
    override def postStop(): Unit = log.info("Actor {} is stopped!", self.path)

    override def preRestart(reason: Throwable, message: Option[Any]): Unit = {
      log.info("In preRestart: reason -> {}, message -> {}", reason.getMessage, message.getOrElse(""))
    }

    def receive = {
      case BadStuff => throw new Exception("Bad Stuff!")

      case _ => log.info("Child Received Message!")
    }
  }`