testRootNode.getSession().save();
assertTrue(n.hasProperty("jcr:uuid"));
// remove mix:title, jcr:title should be gone as there's no matching
// definition in nt:folder
n.removeMixin("mix:referenceable");
testRootNode.getSession().save();
assertFalse(n.hasProperty("jcr:uuid"));
// add mix:referenceable to a nt:unstructured node, jcr:uuid is
// automatically added