Function reclock_committed_upper 

fn reclock_committed_upper<'scope, T, FromTime>(
    bindings: VecCollection<'scope, T, FromTime, Diff>,
    as_of: Antichain<T>,
    committed_uppers: BTreeMap<GlobalId, StreamVec<'scope, T, ()>>,
    id: GlobalId,
    metrics: Arc<SourceMetrics>,
) -> impl Stream<Item = ResumeUppers<FromTime>> + 'static
where
    T: Timestamp + Lattice + TotalOrder,
    FromTime: SourceTimestamp,

Reclocks the per-export IntoTime committed upper streams into FromTime ResumeUppers. This is used for the virtual (through persist) feedback edge so that we convert the IntoTime resumption frontiers into the FromTime frontiers that are used with the source’s OffsetCommiter.