Clarify why /_matrix/federation/v1/event/ returns an array

[JJJollyjim]

Apparently GET /_matrix/federation/v1/event/{eventId} "Retrieves a single event".

The response contains an array pdus which "Must not include more than 50 PDUs".

May it ever include more than one PDU?

What if the same eventId is used in multiple rooms?

[JJJollyjim]

I'm pretty sure the answer is "it always returns one and event IDs duplicated between rooms are undefined behavior".

In that case the field description text in the response schema should probably be changed to something like "List containing a single persistent update to a room. Note that events have a different format depending on the room version - check the room version specification for precise event formats.".

[turt2live]

It returns a Transaction object, which awkwardly has a schema written for the /transaction endpoint. I believe we have words somewhere to say it "must only have 1 event", however this may have been lost in translation.