code: private static OptionalLong fromMetastoreDistinctValuesCount(OptionalLong distinctValuesCount, OptionalLong nullsCount, OptionalLong rowCount)
      {
          if (distinctValuesCount.isPresent() && nullsCount.isPresent() && rowCount.isPresent()) {
              return OptionalLong.of(fromMetastoreDistinctValuesCount(distinctValuesCount.getAsLong(), nullsCount.getAsLong(), rowCount.getAsLong()));
          }
          return OptionalLong.empty();
      }
docs: Hive calculates NDV considering null as a distinct value