if (subIndex != null) {
ClosableMap<Long, ClosableMap<Long, Set<Long>>> subSubIndex = subIndex.get(second);
if (subSubIndex != null) {
final ClosableMap<Long, Set<Long>> map = subSubIndex.get(third);
if (map != null) {
return new FlatteningTwoLongClosableIterator(map);
}
}
}
return new LongArrayEmptyClosableIterator();
}