/** pollFirstEntry returns entries in order */
 public void testDescendingPollFirstEntry() {
   ConcurrentNavigableMap map = dmap5();
   Map.Entry e = map.pollFirstEntry();
   assertEquals(m1, e.getKey());
   assertEquals("A", e.getValue());
   e = map.pollFirstEntry();
   assertEquals(m2, e.getKey());
   map.put(m1, "A");
   e = map.pollFirstEntry();
   assertEquals(m1, e.getKey());
   assertEquals("A", e.getValue());
   e = map.pollFirstEntry();
   assertEquals(m3, e.getKey());
   map.remove(m4);
   e = map.pollFirstEntry();
   assertEquals(m5, e.getKey());
   try {
     e.setValue("A");
     shouldThrow();
   } catch (UnsupportedOperationException success) {
   }
   e = map.pollFirstEntry();
   assertNull(e);
 }
 /** pollFirstEntry returns entries in order */
 public void testPollFirstEntry() {
   ConcurrentNavigableMap map = map5();
   Map.Entry e = map.pollFirstEntry();
   assertEquals(one, e.getKey());
   assertEquals("A", e.getValue());
   e = map.pollFirstEntry();
   assertEquals(two, e.getKey());
   map.put(one, "A");
   e = map.pollFirstEntry();
   assertEquals(one, e.getKey());
   assertEquals("A", e.getValue());
   e = map.pollFirstEntry();
   assertEquals(three, e.getKey());
   map.remove(four);
   e = map.pollFirstEntry();
   assertEquals(five, e.getKey());
   try {
     e.setValue("A");
     shouldThrow();
   } catch (UnsupportedOperationException success) {
   }
   e = map.pollFirstEntry();
   assertNull(e);
 }