SortedMap is not returned when another unrelated method exists in the interface

During testing of bug 4534 I stumbled upon the following behavior. Subsets of tests were passing when run standalone but failing when run in the full test suite.

So I have narrowed it down to one method that fails when another is uncommented in the interface.

Interface:
// uncomment this for the next method to fail
// public Map<String, Map<Integer, Integer>> testDirectComplexMapResult();

// fail – puts data into a hashmap instead of a SortedMap if the above is uncommented
public Map<String, SortedMap<Integer, Integer>> testDirectComplexTreeMapResult();

Implementation:
//@Override
public Map<String, Map<Integer, Integer>> testDirectComplexMapResult()

{ final Map<String, Map<Integer, Integer>> result = new HashMap<String, Map<Integer, Integer>>(); final TreeMap<Integer, Integer> map1 = new TreeMap<Integer, Integer>(); map1.put(1, 3); result.put("key1", map1); return result; }

@Override
public Map<String, SortedMap<Integer, Integer>> testDirectComplexTreeMapResult()

{ final Map<String, SortedMap<Integer, Integer>> result = new HashMap<String, SortedMap<Integer, Integer>>(); final TreeMap<Integer, Integer> map1 = new TreeMap<Integer, Integer>(); map1.put(1, 3); map1.put(0, 2); result.put("key1", map1); return result; }

Client:
@Test
public void testDirectComplexTreeMapResult() {
final Map map = TestServiceFactory.getService()
.testDirectComplexTreeMapResult();
log.info(map);
for (final Object vmap : map.values())

{ Assert.assertTrue(vmap instanceof SortedMap); }

}