public void testDescendingHigherEntry() {
ConcurrentNavigableMap map = dmap5();
Map.Entry e1 = map.higherEntry(m3);
assertEquals(m4, e1.getKey());
Map.Entry e2 = map.higherEntry(zero);
assertEquals(m1, e2.getKey());
Map.Entry e3 = map.higherEntry(m5);
assertNull(e3);