NakAsync not working as expected

[alberk8]

I have the following code, where the NakAsync does not seems to work. The server does not respect the backoff. The foreach loop will run in quick succession for 3 times per message corresponding to the MaxDeliver.

But if the NakAsync is not there then the back off works as expected. Is this a bug?

static async Task Main(string[] args)
{
    Console.WriteLine("Hello, World!");

    NatsOpts opts = new NatsOpts() 
    {
        Url = "nats://192.168.1.1:4222"
    };
    var conn = new NatsConnection(opts);
    var natsJSContext =  new NatsJSContext(conn);
    INatsJSStream natsJSStream;


    var streamConfig = new StreamConfig("TestStream", new[] { "TestSubject" })
    {
        MaxAge = TimeSpan.FromDays(1),
        Compression = StreamConfigCompression.S2,
    };

    try
    {
      
       natsJSStream = await natsJSContext.UpdateStreamAsync(streamConfig);  
    }
    catch (NatsJSApiException e) when (e.Error.Code is 404)
    {
        natsJSStream = await natsJSContext.CreateStreamAsync(streamConfig);
    }

    await natsJSContext.PublishAsync("TestSubject", "Testing");

    var backoff = new List<long>() { (long)10 * 1_000_000_000 ,(long) 15 * 1_000_000_000 };
    var consumerConfig = new ConsumerConfig("TestConsumer2")
    {
        FilterSubject = "TestSubject",
        DeliverPolicy = ConsumerConfigDeliverPolicy.All,
        AckPolicy = ConsumerConfigAckPolicy.Explicit,
        AckWait = TimeSpan.FromSeconds(10),
        Backoff = backoff,
        MaxDeliver = 3
    };

    var consumer = await natsJSContext!.CreateOrUpdateConsumerAsync("TestStream", consumerConfig);

    await foreach (NatsJSMsg<string> msg in consumer.ConsumeAsync<string>())
    {
        if (msg.Metadata.HasValue)
        {
            Console.WriteLine($"Sequence: {msg.Metadata.Value.Sequence.Stream}");
        }
        
        await msg.NakAsync();
    }
   
    Console.WriteLine("Done");
}