docs: public static CoreMap getMergedChunk(List<? extends CoreMap> chunkList,
                                         int chunkIndexStart, int chunkIndexEnd,
                                         Map<Class, CoreMapAttributeAggregator> aggregators)
    {
      CoreMap newChunk = new Annotation("");
      for (Map.Entry<Class,CoreMapAttributeAggregator> entry:aggregators.entrySet()) {
        if (chunkIndexEnd > chunkList.size()) {
          assert(false);
        }
        Object value = entry.getValue().aggregate(entry.getKey(), chunkList.subList(chunkIndexStart, chunkIndexEnd));
        newChunk.set(entry.getKey(), value);
      }
      return newChunk;
    }