### Question:
CollectionUtils { public static <S, T> Dictionary<S, T> singletonDictionary(S s, T t) { return toDictionary(Collections.singletonMap(s, t)); } 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 testSingletonDictionary() throws Exception { String key = "k"; String value = "v"; Dictionary<String, String> d = CollectionUtils.singletonDictionary(key, value); assertNotNull(d.elements()); assertEquals(value, d.get(key)); assertFalse(d.isEmpty()); assertNotNull(d.keys()); assertEquals(1, d.size()); }