CaselessUnmodifiableMultivaluedMap extends CaselessMultivaluedMap<T> { @Override public List<T> get(Object key) { List<T> list = super.get(key); if (list != null) { return Collections.unmodifiableList(list); } return null; } CaselessUnmodifiableMultivaluedMap();  CaselessUnmodifiableMultivaluedMap(int capacity);  CaselessUnmodifiableMultivaluedMap(Map<String, List<T>> m); @Override void add(String key, T value); @Override void clear(); @Override Set<Entry<String, List<T>>> entrySet(); @Override List<T> get(Object key); @Override List<T> getList(String key); @Override Set<String> keySet(); @Override List<T> put(String key, List<T> value); @Override void putAll(Map<? extends String, ? extends List<T>> m); @Override void putSingle(String key, T value); @Override List<T> remove(Object key); @Override void addAll(String key, T... newValues); @Override void addAll(String key, List<T> valueList); @Override void addFirst(String key, T value); @Override Collection<List<T>> values();  }
@Test public void testGet() { assertEquals("a", map.getFirst("k")); assertEquals(Arrays.asList("a", "b"), map.get("k")); assertEquals("c", map.getFirst("E")); assertEquals(Arrays.asList("d", "e"), map.get("Y")); }