code: @Override
    public int advance(int target) throws IOException {
      resetQueue();
      Integer newTarget = target;
      do {
        newTarget = advanceToDoc(newTarget);
      } while (newTarget != null);
      return docId;
    }
docs: /*
  (non-Javadoc)
  
  @see org.apache.lucene.search.DocIdSetIterator#advance(int)