### Question:
CollectionUtils { public static boolean isEmpty(Collection coll) { return coll == null || coll.isEmpty(); } private  CollectionUtils(); static Collection<T> subtract(Set<T> a, Set<T> b); static boolean isNotEmpty(Collection coll); static boolean isEmpty(Collection coll); static Map<String, String> stringToMap(String str, String separator); static Map<String, String> stringToMap(String str, String separator, String keyPrefix); static boolean equalLists(Collection<?> a, Collection<?> b); static boolean isEqualCollection(final Collection<?> a, final Collection<?> b); static Map<O, Integer> getCardinalityMap(final Iterable<? extends O> coll); static List<Map<String, Object>> getListByExclusion(List<T> originList, Set<String> exclusionSet);  }### Answer:
@Test public void isEmpty(){ List<Integer> list = new ArrayList<>(); Assert.assertTrue(CollectionUtils.isEmpty(list)); Assert.assertTrue(CollectionUtils.isEmpty(null)); list.add(1); Assert.assertFalse(CollectionUtils.isEmpty(list)); }