The (old) RFC 7540 has:

Pseudo-header fields defined for requests MUST NOT appear
in responses; pseudo-header fields defined for responses MUST NOT
appear in requests. Pseudo-header fields MUST NOT appear in
trailers.

Where are we doing that first part? I'd expect to see the mirror of this logic elsewhere. Do we just not have that logic anywhere?

Originally posted by @ejona86 in #13603 (review)

Need to validate Netty's behavior on this and if appropriate work on a fix to validate