docs: private org.apache.hadoop.conf.Configuration mirrorCertainHadoopConfig(
  		org.apache.hadoop.conf.Configuration hadoopConfig) {
  		for (String[] mirrored : mirroredConfigKeys) {
  			String value = hadoopConfig.get(mirrored[0], null);
  			if (value != null) {
  				hadoopConfig.set(mirrored[1], value);
  			}
  		}
  		return hadoopConfig;
  	}