public List<TaskHandler> getHandlers(HiveConf conf, TxnStore txnHandler, MetadataCache metadataCache,
                                                  boolean metricsEnabled, FSRemover fsRemover) {
    boolean useAbortHandler = MetastoreConf.getBoolVar(conf, MetastoreConf.ConfVars.COMPACTOR_CLEAN_ABORTS_USING_CLEANER);
    List<TaskHandler> taskHandlers = new ArrayList<>();
    taskHandlers.add(new CompactionCleaner(conf, txnHandler, metadataCache,
            metricsEnabled, fsRemover));
    if (useAbortHandler) {
      taskHandlers.add(new AbortedTxnCleaner(conf, txnHandler, metadataCache,
              metricsEnabled, fsRemover));
    }
    return taskHandlers;
  }
Factory class, no need to expose constructor.
ql/src/java/org/apache/hadoop/hive/ql/txn/compactor/handler/TaskHandlerFactory.java