private List<MOrder> convertToMOrders(List<Order> keys) {
    List<MOrder> mkeys = null;
    if (keys != null) {
      mkeys = new ArrayList<>();
      for (Order part : keys) {
        mkeys.add(new MOrder(normalizeIdentifier(part.getCol()), part.getOrder()));
      }
    }
    return mkeys;
  }
Makes shallow copy of a map to avoid DataNucleus mucking with our objects.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/ObjectStore.java