final String p = o.toString();
if (!orderByProperties.containsKey(p)) {
orderByProperties.put(p, o);
}
}
final DynamicOperandFieldComparatorSource dofcs = new DynamicOperandFieldComparatorSource(
session, evaluator, orderByProperties);
List<SortField> sortFields = new ArrayList<SortField>();
// as it turn out, orderByProperties.keySet() doesn't keep the original