@Override
		public Observable<PartitionAndOffset> call(GroupedObservable<Partition, PartitionAndOffset> group) {
			return Observable.zip(Observable.just(group.getKey()),
					MathObservable.max(group.map(getOffsetFunction)),
					createPartitionAndOffsetFunction);
		}
The timeout that {@link #close()} and {@link #destroy()} operations will wait for receving a confirmation that the
underlying writes have been processed.

@param shutdownTimeout duration in milliseconds
extensions/spring-xd-extension-kafka/src/main/java/org/springframework/integration/x/kafka/WindowingOffsetManager.java