Method null_count

cpp/src/parquet/statistics.cc:818–818

  }

  int64_t null_count() const override { return statistics_.null_count; }
  int64_t distinct_count() const override { return statistics_.distinct_count; }
  int64_t num_values() const override { return num_values_; }
  std::optional<bool> is_min_value_exact() const override {