OptionalduplicateApplies to events in the timeline only. If this is 'replace' then if a duplicate is encountered, the event passed to this function will replace the existing event in the timeline. If this is not specified, or is 'ignore', then the event passed to this function will be ignored entirely, preserving the existing event in the timeline. Events are identical based on their event ID only.
OptionalfromWhether the sync response came from cache
OptionalroomThe state events to reconcile metadata from
OptionaltimelineWhether the timeline was empty before the marker event arrived in the room. This could be happen in a variety of cases:
syncFromCacheA marker event refers to UNSTABLE_MSC2716_MARKER and indicates that
history was imported somewhere back in time. It specifically points to an
MSC2716 insertion event where the history was imported at. Marker events
are sent as state events so they are easily discoverable by clients and
homeservers and don't get lost in timeline gaps.
Whether to add timeline events to the state as was done in legacy sync v2. If true then timeline events will be added to the state. In sync v2 with org.matrix.msc4222.use_state_after and simplified sliding sync, all state arrives explicitly and timeline events should not be added.