Using GroupAlsoByWindowViaWindowSetDoFn for stream of input element

[Thomas Weise]

Hi,

I'm looking into using the GroupAlsoByWindowViaWindowSetDoFn to accumulate
the windowed state with the elements arriving one by one (stream).

Once the window is complete, I would like to emit an Iterable<V> or another
form of aggregation of the elements. Is the following supposed to lead to
merging of current element with previously received elements for the same
window:

    KeyedWorkItem<K, V> kwi = KeyedWorkItems.elementsWorkItem(
            kv.getKey(),
            Collections.singletonList(updatedWindowedValue));

    context.setElement(kwi, getStateInternalsForKey(kwi.key()));
    fn.processElement(context);

The input here are always single elements.

Thanks,
Thomas