Search/context endpoint doesn't mention a user_id

[S7evinK]

Link to problem area:
https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3search
https://spec.matrix.org/v1.3/client-server-api/#get_matrixclientv3roomsroomidcontexteventid

Issue
Question came up in matrix-org/sytest#1281
The /search endpoint doesn't specify a user_id in any of the response objects, yet Sytest is checking for the existence of this field.
I couldn't find user_id in any older spec version, so the question is what's the correct behavior. Do we need user_id (as currently returned by Synapse in search_categories.room_events.results[] and search_categories.room_events.results[].context.events_before[] (and events_after), or don't we need it?

Same question for /context returned values - Synapse returns a user_id in ClientEvent, while the spec doesn't mention it.

[richvdh]

Looking harder at this, it sounds like a (known) Synapse bug: matrix-org/synapse#7925

[richvdh]

(If you go back far enough, it does exist in the spec. But this is definitely a synapse bug nowadays.)

[turt2live]

(for keywords: this will be an event format issue, as we're on v2 events at a minimum right now)