private static List<ColStatistics> estimateStats(List<ColumnInfo> schema,
      List<String> neededColumns, HiveConf conf, long nr) {

    List<ColStatistics> stats = new ArrayList<>(neededColumns.size());
    for (String column : neededColumns) {
      ColStatistics cs = estimateColStats(nr, column, conf, schema);
      stats.add(cs);
    }
    return stats;
  }
Convert ColumnStatisticsObj to ColStatistics
@param cso
         - ColumnStatisticsObj
@param colName
         - column name
@return ColStatistics
ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java