Make network.type opt-in for HTTP semconv spans and metrics?

[trask]

I'm not sure that knowing ipv4 vs ipv6 is a generally useful piece of data in the scope of HTTP semconv (worth capturing by default on all HTTP spans).

Should we remove it, or explicitly make it opt-in?

[lmolkova]

Assuming the backend does not want to parse the IP address it does not need the type. It's still obvious (on traces) if the network.peer.address is IPv4 or IPv6. Even if instrumentations don't populate it, backends MAY figure out the type.

But metrics are more interesting: I assume it might be interesting how much traffic is coming over ipv4 vs ipv6.

I'd be in favor of keeping it on traces, adding to metrics, and making it opt-in on both.