@Test
public void test_emptyDoesntCallCallback() {

  final int[] accessor = {999};
  Map<String, Integer> testMap =
      new ReferenceCountedHashMap<>(
          new Callable<Integer>() {
            @Override
            public void call(Integer input) {
              accessor[0] = input;
            }
          });
  Assert.assertNull(testMap.remove(KEYS[0]));
  Assert.assertEquals(accessor[0], 999);
}