d85b45ed64
The ordering criteria is defined at https://spec.matrix.org/latest/client-server-api/#ordering-of-children-within-a-space. The gist is that `order` comes first, then `timestamp` and finally the `room_id` This is not available for top level spaces, but there is an MSC that addresses it at https://github.com/matrix-org/matrix-spec-proposals/pull/3230 and Ruma support has been added in https://github.com/ruma/ruma/pull/2231. The SDK side implementation for that will come in a later PR.