/** Collect documents from a bitset. */ private List<Document> collectDocuments(List<Document> l, BitSet bitset) { if (l == null) { l = Lists.newArrayListWithCapacity((int) bitset.cardinality()); } final BitSetIterator i = bitset.iterator(); for (int d = i.nextSetBit(); d >= 0; d = i.nextSetBit()) { l.add(documents.get(d)); } return l; }