code: public static void initializeComparators(Configuration conf, TupleMRConfig groupConfig) {
      TupleMRConfigBuilder.initializeComparators(conf, groupConfig.getCommonCriteria());
      for (Criteria criteria : groupConfig.getSpecificOrderBys()) {
        if (criteria != null) {
          TupleMRConfigBuilder.initializeComparators(conf, criteria);
        }
      }
    }
docs: Initializes the custom comparator instances inside the given config
  criterias, calling the {@link Configurable#setConf(Configuration)} method.