private String createDefaultLbDir(List<String> skewedCols,
      Map<List<String>, String> locationMap) {
    String lbDirName;
    lbDirName = FileUtils.makeDefaultListBucketingDirName(skewedCols,
          lbCtx.getDefaultDirName());
    List<String> defaultKey = Lists.newArrayList(lbCtx.getDefaultKey());
    if (!locationMap.containsKey(defaultKey)) {
      locationMap.put(defaultKey, lbDirName);
    }
    return lbDirName;
  }
Generate list bucketing directory name from a row.
@param row row to process.
@return directory name.
ql/src/java/org/apache/hadoop/hive/ql/exec/FileSinkOperator.java