new Mapper<Iterable<Object>, OrderHistory>() {
public OrderHistory apply(Iterable<Object> coll) {
final Iterator<Object> it = coll.iterator();
final Order order = (Order) it.next();
final Address address = (Address) it.next();
return new OrderHistory(order, address);
}
}, getContext().system().dispatcher());
// aggregated result is piped to another actor
pipe(aggResult, getContext().system().dispatcher()).to(
orderAggregateActor);