Or, perhaps, making use of a more fluent API:

R result = new MapReduceTask(cache).on(K...).mappedWith(mapper).reducedWith(reducer).collate(collator);

Future<R>  result = new MapReduceTask(cache).on(K...).mappedWith(mapper).reducedWith(reducer).collateAsynchronously(collator);

List<R>  result = new DistributedRemoteTask(cache).on(K...).execute(distributedCallable);

List<Future<R>>  result = new DistributedRemoteTask(cache).on(K...).executeAsync(distributedCallable);

Awesome! I love this fluent API proposal!