code: public static boolean datasetAlreadyCompacted(FileSystem fs, Dataset dataset, boolean renameSourceEnable) {
      if (renameSourceEnable) {
        return checkAlreadyCompactedBasedOnSourceDirName (fs, dataset);
      } else {
        return checkAlreadyCompactedBasedOnCompletionFile(fs, dataset);
      }
    }
docs: A {@link Dataset} is considered already compacted if either condition is true:
  1) When completion file strategy is used, a compaction completion means there is a file named
  {@link MRCompactor#COMPACTION_COMPLETE_FILE_NAME} in its {@link Dataset#outputPath()}.
  2) When renaming source directory strategy is used, a compaction completion means source directories
  {@link Dataset#inputPaths()} contains at least one directory which has been renamed to something with
  {@link MRCompactor#COMPACTION_RENAME_SOURCE_DIR_SUFFIX}.