docs: private Object finalizeConversion(Object o)
    {
      // conversion can leave 'wrapped' list primitives
      if (ParquetGroupConverter.isWrappedListPrimitive(o)) {
        return converter.unwrapListPrimitive(o);
      } else if (o instanceof List) {
        List<Object> asList = ((List<Object>) o).stream().filter(Objects::nonNull).collect(Collectors.toList());
        if (asList.stream().allMatch(ParquetGroupConverter::isWrappedListPrimitive)) {
          return asList.stream().map(Group.class::cast).map(converter::unwrapListPrimitive).collect(Collectors.toList());
        }
      }
      return o;
    }