override val address = factory.newAddress("example.com")

  fun addPlan(): FakePlan {
    return FakePlan(nextPlanId++).also {
      plans += it
    }
  }

  override fun isCanceled() = canceled

  override fun plan(): FakePlan {
    // Return deferred plans preferentially. These don't require addPlan().
    if (deferredPlans.isNotEmpty()) return deferredPlans.removeFirst() as FakePlan