code: public ScoreNode nextScoreNode() throws IOException {
          while (childHits != null) {
              ScoreNode sn = childHits.nextScoreNode();
              if (sn != null) {
                  return sn;
              } else {
                  fetchNextChildHits();
              }
          }
          // if we get here there are no more score nodes
          return null;
      }
docs: {@inheritDoc}