ForkJoinStream<T, R> constructor
Constructs a Stream that awaits the last values of the Streams
in streams, then calls the combiner to emit an event of type R.
After this event, the Stream closes.
Implementation
ForkJoinStream(
Iterable<Stream<T>> streams,
R Function(List<T> values) combiner,
) : super(_buildStream(streams, combiner));