How to use Oracle hints in your query
You can use a ProjectionList as shown in this example:
ProjectionList proList = Projections.projectionList();
proList.add(Projections.sqlProjection("/*+INDEX_DESC(this_INDEX_NAME)*/ 1 as MYHINT", new String[]{}, new Type[]{}));
//add properties from your class
proList.add(Projections.property("field1"));
proList.add(Projections.property("field2"));
proList.add(Projections.property("field3"));
c.setProjection(proList);