### Question:
MultiMapUtils { public static boolean isEmpty(final MultiValuedMap<?, ?> map) { return map == null || map.isEmpty(); } private  MultiMapUtils(); @SuppressWarnings("unchecked") static MultiValuedMap<K, V> emptyMultiValuedMap(); @SuppressWarnings("unchecked") static MultiValuedMap<K, V> emptyIfNull(final MultiValuedMap<K, V> map); static boolean isEmpty(final MultiValuedMap<?, ?> map); static Collection<V> getCollection(final MultiValuedMap<K, V> map, final K key); static List<V> getValuesAsList(final MultiValuedMap<K, V> map, final K key); static Set<V> getValuesAsSet(final MultiValuedMap<K, V> map, final K key); static Bag<V> getValuesAsBag(final MultiValuedMap<K, V> map, final K key); static ListValuedMap<K, V> newListValuedHashMap(); static SetValuedMap<K, V> newSetValuedHashMap(); static MultiValuedMap<K, V> unmodifiableMultiValuedMap(
            final MultiValuedMap<? extends K, ? extends V> map); static MultiValuedMap<K, V> transformedMultiValuedMap(final MultiValuedMap<K, V> map,
            final Transformer<? super K, ? extends K> keyTransformer,
            final Transformer<? super V, ? extends V> valueTransformer); @SuppressWarnings({ "rawtypes", "unchecked" })
    static final MultiValuedMap EMPTY_MULTI_VALUED_MAP; }### Answer:
@Test @SuppressWarnings({ "unchecked", "rawtypes" }) public void testEmptyUnmodifiableMultiValuedMap() { final MultiValuedMap map = MultiMapUtils.EMPTY_MULTI_VALUED_MAP; assertTrue(map.isEmpty()); try { map.put("key", "value"); fail("Should throw UnsupportedOperationException"); } catch (UnsupportedOperationException e) { } }
@Test public void testIsEmptyWithEmptyMap() { final MultiValuedMap<Object, Object> map = new ArrayListValuedHashMap<Object, Object>(); assertEquals(true, MultiMapUtils.isEmpty(map)); }
@Test public void testIsEmptyWithNonEmptyMap() { final MultiValuedMap<String, String> map = new ArrayListValuedHashMap<String, String>(); map.put("item", "value"); assertEquals(false, MultiMapUtils.isEmpty(map)); }
@Test public void testIsEmptyWithNull() { final MultiValuedMap<Object, Object> map = null; assertEquals(true, MultiMapUtils.isEmpty(map)); }