code: public ScoreNode nextScoreNode() throws IOException
     {
        if (scorer == null)
        {
           return null;
        }
        int doc = scorer.nextDoc();
        if (doc == DocIdSetIterator.NO_MORE_DOCS)
        {
           return null;
        }
        String uuid = reader.document(doc).get(FieldNames.UUID);
        return new ScoreNode(uuid, scorer.score(), doc);
     }
docs: {@inheritDoc}