@Override
  public void acquireLocks(QueryPlan plan, Context ctx, String username) throws LockException {
    acquireLocks(plan,ctx,username,null);
  }
An implementation of {@link HiveTxnManager} that does not support
transactions.  This provides default Hive behavior.
ql/src/java/org/apache/hadoop/hive/ql/lockmgr/DummyTxnManager.java