I have a question about signature handling in #ActivityPub relays. As I understand it, relays forward activities between instances that aren't directly connected. Let's say we have this flow: foo.com (source) → bar.com (relay) → baz.com (destination). The activity created by foo.com includes HTTP Signatures, but when bar.com forwards it to baz.com, wouldn't the original signature become invalid since the Host header needs to change? How do relay implementations handle this issue?
