Function full_conflicted_set 

async fn full_conflicted_set<AuthSets, FetchExists, ExistsFut, FetchEvent, EventFut, Pdu>(
    rules: &RoomVersionRules,
    conflicted_states: ConflictMap<OwnedEventId>,
    auth_sets: AuthSets,
    fetch: &FetchEvent,
    exists: &FetchExists,
    backport_css: bool,
) -> HashSet<OwnedEventId>
where
    AuthSets: Stream<Item = AuthSet<OwnedEventId>> + Send,
    FetchExists: Fn(OwnedEventId) -> ExistsFut + Sync,
    ExistsFut: Future<Output = bool> + Send,
    FetchEvent: Fn(OwnedEventId) -> EventFut + Sync,
    EventFut: Future<Output = Result<Pdu>> + Send,
    Pdu: Event,