Root root = new Root();
root.setID(222);
// Only set the list I wan't let the other fields be null and hibernate shouldn't touch them in the db
List<Foo> listWhoWantsToBeMerged = new ArrayList<Foo>();
listWhoWantsToBeMerged.add(new Foo("Add me to the list in db please"));
root.setList(listWhoWantsToBeMerged);
RootDao.mergeList(root);