After upgrading to v1.20.0 and kadm/v1.17.0 metadata requests now return empty results. I think this might have something to do with the metadata cache changes.

Simple poc repo if needed; https://github.com/countableSet/franz-go-1142

I tracked it to this commit 30ed0f3 that now uses method RequestCachedMetadata

fn := func() (*kmsg.MetadataResponse, error) {
	return cl.cl.RequestCachedMetadata(ctx, req, 0)
}

In the case of no topics provided to metadata request

if noTopics {
	req.Topics = []kmsg.MetadataRequestTopic{}
}

fetchMappedMetadata within the client the request metadata cache will have an empty slice of topics

and fetchCachedMappedMetadata will return return nil, ts

this causes len(needed) == 0 and intoMapped == nil

Thus always returning nil metadata and not reaching the actual fetch request here.