static <E> ImmutableSet<E> asImmutable(Set<E> delegate) {
    switch (delegate.size()) {
      case 0:
        return ImmutableSet.of();
      case 1:
        return ImmutableSet.of(Iterables.getOnlyElement(delegate));
      default:
        return new ImmutableEnumSet<E>(delegate);
    }
  }

  public ImmutableEnumSet(Set<E> delegate) {
    super(delegate);
  }

    interfaces.remove(AutoCloseable.class);
    @SuppressWarnings("unchecked") // super interface type of T
    Class<? super T> interfaceType = (Class<? super T>) Iterables.getOnlyElement(interfaces);
    new ForwardingWrapperTester()
        .testForwarding(
            interfaceType,
            delegate -> {
              T mock = mock(forwarderClass, CALLS_REAL_METHODS);
              try {

    interfaces.remove(AutoCloseable.class);
    @SuppressWarnings("unchecked") // super interface type of T
    Class<? super T> interfaceType = (Class<? super T>) Iterables.getOnlyElement(interfaces);
    new ForwardingWrapperTester()
        .testForwarding(
            interfaceType,
            delegate -> {
              T mock = mock(forwarderClass, CALLS_REAL_METHODS);
              try {

    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());

    assertThrows(IllegalStateException.class, service::startAsync);
    assertEquals(State.TERMINATED, Iterables.getOnlyElement(listener.getStateHistory()));
  }

  public void testFailingServiceStartAndWait() throws Exception {
    StartFailingService service = new StartFailingService();

    service.stopAsync();
    assertEquals(State.TERMINATED, service.state());

    assertThrows(IllegalStateException.class, service::startAsync);
    assertEquals(State.TERMINATED, Iterables.getOnlyElement(listener.getStateHistory()));
  }

  public void testFailingServiceStartAndWait() throws Exception {
    StartFailingService service = new StartFailingService();

      assertThat(future.isDone()).isTrue();
      // inspect state and ensure it is correct!
      // asserts that all get calling threads received the same value
      Object result = Iterables.getOnlyElement(finalResults);
      if (result == CancellationException.class) {
        assertTrue(future.isCancelled());
        if (future.wasInterrupted()) {

      assertThat(future.isDone()).isTrue();
      // inspect state and ensure it is correct!
      // asserts that all get calling threads received the same value
      Object result = Iterables.getOnlyElement(finalResults);
      if (result == CancellationException.class) {
        assertTrue(future.isCancelled());
        if (future.wasInterrupted()) {

    RuntimeException re = new RuntimeException(iae);
    IllegalStateException ex = new IllegalStateException(re);

    assertThat(getCausalChain(ex)).containsExactly(ex, re, iae, sue).inOrder();
    assertThat(Iterables.getOnlyElement(getCausalChain(sue))).isSameInstanceAs(sue);

    List<Throwable> causes = getCausalChain(ex);
    assertThrows(UnsupportedOperationException.class, () -> causes.add(new RuntimeException()));
  }

    RuntimeException re = new RuntimeException(iae);
    IllegalStateException ex = new IllegalStateException(re);

    assertThat(getCausalChain(ex)).containsExactly(ex, re, iae, sue).inOrder();
    assertThat(Iterables.getOnlyElement(getCausalChain(sue))).isSameInstanceAs(sue);

    List<Throwable> causes = getCausalChain(ex);
    assertThrows(UnsupportedOperationException.class, () -> causes.add(new RuntimeException()));
  }

    }
  }

  public void testWriteThroughEntry() {
    for (LoadingCache<Object, Object> cache : caches()) {
      cache.getUnchecked(1);
      Entry<Object, Object> entry = Iterables.getOnlyElement(cache.asMap().entrySet());

      cache.invalidate(1);
      assertThat(cache.size()).isEqualTo(0);

      entry.setValue(3);
      assertThat(cache.size()).isEqualTo(1);