### Question:
CollectionUtils { public static <T> boolean isEmpty(Collection<T> c) { if (c != null && !c.isEmpty()) { for (T item : c) { if (item != null) { return false; } } } return true; } private  CollectionUtils(); static Collection<T> diff(Collection<T> c1, Collection<T> c2); static boolean isEmpty(Collection<T> c); static boolean isEmpty(Map<K, V> m); static Dictionary<S, T> singletonDictionary(S s, T t); static Dictionary<S, T> toDictionary(Map<S, T> map);  }### Answer:
@Test public void testIsEmpty() throws Exception { assertTrue(CollectionUtils.isEmpty((Collection) null)); assertTrue(CollectionUtils.isEmpty((Map) null)); Collection<String> l = Arrays.asList(null, null); assertTrue(CollectionUtils.isEmpty(l)); }