Function encode_updates 

fn encode_updates<'s, T, D, CB>(
    collection: VecCollection<'s, T, D, Diff>,
    name: &str,
) -> Stream<'s, T, CB::Container>
where
    T: Timestamp,
    D: Data,
    CB: ContainerBuilder + PushInto<(D, T, Diff)> + 'static,

Re-encodes a Vec collection through CB.

For a join implementation that builds its own Vec output and so cannot be handed a container builder.