internal async Task RemoveActivePlan(ActiveAsyncPlan activePlan)
        {
            _activePlans.Remove(activePlan);

            if (_activePlans.Count == 0)
            {
                await DisposeAsync().ConfigureAwait(false);
            }
        }
 public void AddActivePlan(ActiveAsyncPlan activePlan)
 {
     _activePlans.Add(activePlan);
 }