Mark recv meta as non exhaustibe

[gretchenfrage]

Per #2339 I think we should consider marking recv meta as non exhaustive so that subsequent field additions are not breaking

[mxinden]

I am in favor. @gretchenfrage let me know if you want me to propose a patch.

[gretchenfrage]

@mxinden yeah I mean this is a +1 -0 change right? I'd approve if you opened a PR :)

[mxinden]

Sorry for the delay @gretchenfrage. See #2388.

[gretchenfrage]

No worries friend I'm just chilling