}

  public void testValues() {
    Map<String, Integer> map = create();
    Collection<Integer> values = map.values();
    assertTrue(values instanceof SynchronizedCollection);
    assertSame(mutex, ((SynchronizedCollection<?>) values).mutex);
  }

  public void testEntrySet() {
    Map<String, Integer> map = create();
    Set<Entry<String, Integer>> entrySet = map.entrySet();

  }

  public void testValues() {
    Map<String, Integer> map = create();
    Collection<Integer> values = map.values();
    assertTrue(values instanceof SynchronizedCollection);
    assertSame(mutex, ((SynchronizedCollection<?>) values).mutex);
  }

  public void testEntrySet() {
    Map<String, Integer> map = create();
    Set<Entry<String, Integer>> entrySet = map.entrySet();

      Collection<E> collection, @CheckForNull Object mutex) {
    return new SynchronizedCollection<>(collection, mutex);
  }

  @VisibleForTesting
  static class SynchronizedCollection<E extends @Nullable Object> extends SynchronizedObject
      implements Collection<E> {
    private SynchronizedCollection(Collection<E> delegate, @CheckForNull Object mutex) {
      super(delegate, mutex);
    }

      Collection<E> collection, @CheckForNull Object mutex) {
    return new SynchronizedCollection<>(collection, mutex);
  }

  @VisibleForTesting
  static class SynchronizedCollection<E extends @Nullable Object> extends SynchronizedObject
      implements Collection<E> {
    private SynchronizedCollection(Collection<E> delegate, @CheckForNull Object mutex) {
      super(delegate, mutex);
    }