jetstream.CreateOrUpdateKeyValue doesn't handle the Domain property of jetstream.ExternalStream correctly when mirroring

[the-plash]

Observed behavior

I have a simple setup with a leaf node connected to a hub. Jetstream is separated into two different domains ("hub" and "leaf") and i'm trying to mirror a bucket named "my_bucket" from the hub to the leaf node.

This is the code I'm using:

kv, err := leafJs.CreateOrUpdateKeyValue(ctx, jetstream.KeyValueConfig{
	Bucket:      "my_bucket",
	Mirror: &jetstream.StreamSource{
		Name:     "my_bucket",
		Domain: "hub",
	},
})

But this produces the following error on the leaf node:
nats: API error: code=500 err_code=10052 description=detected cycle

Upon further inspection, the issue may be related to CreateOrUpdateKeyValue requesting a Jetstream API call to $JS.API.STREAM.UPDATE.KV_my_bucket without the proper external property in the mirror map.

If I change the previous code to

kv, err := leafJs.CreateOrUpdateKeyValue(ctx, jetstream.KeyValueConfig{
	Bucket:      "my_bucket",
	Mirror: &jetstream.StreamSource{
		Name:     "my_bucket",
		// Domain: "hub",
		External: &jetstream.ExternalStream{APIPrefix: "$JS.hub.API"},
	},
})

manually specifying the correct APIPrefix (instead of relying on the library compiling it from the Domain property) everything works as expected.

Expected behavior

The previous code should run just fine when specifying only the Domain property of the StreamSource instead

Server and client version

• Leaf node server version: 2.10.12
• Hub server version: 2.10.12
• github.com/nats-io/nats.go v1.34.0
• go version go1.22.0 windows/amd64

Host environment

No response

Steps to reproduce

No response

[piotrpio]

Hello @the-plash, thanks for creating the issue, I'll look at this.