@Override
            public BiConsumer<List<T>, T> accumulator() {
                return (accumulator, item) -> {
                    if (pageRequest == null
                        || (
                                counter >= pageRequest.getOffset() &&
                                accumulator.size() < pageRequest.getLength())) {
                        accumulator.add(item);
                    }
                    counter++;
                };
            }
Used for filter queries (maybe bounded).
stroom-util-shared/src/main/java/stroom/util/shared/ResultPage.java