synapse allows you to omit the `from` param to /messages, which is non-spec-compliant

[richvdh]

Per https://matrix.org/docs/spec/client_server/r0.5.0#get-matrix-client-r0-rooms-roomid-messages, from is mandatory, but apparently riot-android does not (always?) set it.

[ShadowJonathan]

(Updated spec link, for reference: https://matrix.org/docs/spec/client_server/latest#get-matrix-client-r0-rooms-roomid-messages)

[deepbluev7]

Duplicate of #1445, I'd say.

[clokep]

See also MSC3567 which looks to standardize the behavior in Synapse.

[clokep]

This behavior is now spec compliant, per MSC3567.