Unable to subscribe an enpoint to multiple pub-subs

[mmisztal1980]

Expected Behavior

Having registered multiple different pubsubs (redis streams & rabbit) to an endpoint, I expected that the endpoint would subscribe to all of them. This was interesting to me because I was testing if I could have HA on the pubsub(s) by having multiple instances of it (for instance 2x separate rabbitmq instances)

Actual Behavior

When using .WithTopic multiple times, it appears that the last registered pubsub wins.

I've tested it by :

• commenting out the 2nd pubsub, to verify that the 1st pubsub works as intended
• inverting the order in which pubsubs were registered to verify that "last one wins" theory - the test confirmed it.

Why I feel this is not the expected behavior:

• The IEndpointConventionBuilder's .WithTopic fluent API seems to be designed to allow such situation(s).
• The .WithTopic xml docs does not explicitly state that this is not allowed
• Under the hood, .WithTopic adds a TopicAttribute to the underlying builder's metadata - which should conceptually work at 1st glance
• I can imagine a scenario where a event can originate from 2 different sources. Therefore I'd like to adhere to the DRY rule and handle the said event at a single location

Steps to Reproduce the Problem

Sample C# code to reproduce the problem:

endpoints
   .MapPost("/orders", async context =>
  {
    var order = await JsonSerializer.DeserializeAsync<Order>(context.Request.Body);
    this.Service.Logger.LogInformation($"Order {order.Id} received");                        
  })
  .WithTopic(Constants.PubSub.RedisStreams, Constants.OrdersTopicName)
  .WithTopic(Constants.PubSub.RabbitMq, Constants.OrdersTopicName);

Release Note

RELEASE NOTE:
Fixed an issue which prevented registering multiple pubsub subscriptions on to an endpoint.

[rynowak]

@halspang - can you look into this?

[halspang]

@rynowak - Testing this out myself and it is stopping me from subscribing to two topics as well.

Current working theory is that the metadata that we're adding to the builder is overwriting old metadata instead of adding more. I'll look deeper and find a solution.