that should be fine, but I would like to change to

  def scheduleDequeue(delay: FiniteDuration): Unit = inboundThrottleMode match {
    case Blackhole                   ⇒ // Do nothing
    case _ if delay <= Duration.Zero ⇒ self ! Dequeue
    case _                           ⇒ setTimer(DequeueTimerName, Dequeue, delay, repeat = false)
  }

1.nanos feels like a magic number that we don't really need