Optional ReadonlyconcurrencyOptional ReadonlypeerThe peer's Facebook-side user id (ig_user_fbid), local app state. The
profile-updates query is skipped when the caller does not pass it.
ReadonlypeerThe other participant of the 1:1 thread (GetUserSharingInfo's user_id).
ReadonlythreadThe thread's v2 id.
Requests in flight at once inside a stage (default 10).