return delegate.equals(o);
    }

    @Override
    public int hashCode() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.hashCode();
    }

    @Override
    public int size() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.size();
    }

    @Override
    public boolean isEmpty() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.isEmpty();
    }

   */
  private final transient EnumSet<E> delegate;

  private ImmutableEnumSet(EnumSet<E> delegate) {
    this.delegate = delegate;
  }

  @Override
  boolean isPartialView() {
    return false;
  }

  @Override
  public UnmodifiableIterator<E> iterator() {
    return Iterators.unmodifiableIterator(delegate.iterator());
  }

  @Override
  public Spliterator<E> spliterator() {

        return toolchain instanceof ToolchainWrapperV3 v3tc ? v3tc.delegate : new ToolchainWrapperV4(toolchain);
    }

    private ToolchainPrivate getToolchainV3(org.apache.maven.api.Toolchain toolchain) {
        return toolchain instanceof ToolchainWrapperV4 v3tc ? v3tc.delegate : new ToolchainWrapperV3(toolchain);
    }

    private record ToolchainWrapperV4(ToolchainPrivate delegate) implements org.apache.maven.api.Toolchain {

  @Override
  protected abstract ListeningExecutorService delegate();

  @Override
  public <T extends @Nullable Object> ListenableFuture<T> submit(Callable<T> task) {
    return delegate().submit(task);
  }

  @Override
  public ListenableFuture<?> submit(Runnable task) {
    return delegate().submit(task);
  }

  @Override

  public void testListeningDecorator_noWrapExecuteTask() {
    ExecutorService delegate = mock(ExecutorService.class);
    ListeningExecutorService service = listeningDecorator(delegate);
    Runnable task =
        new Runnable() {
          @Override
          public void run() {}
        };
    service.execute(task);
    verify(delegate).execute(task);
  }

  @Override
  protected abstract Multimap<K, V> delegate();

  @Override
  public Map<K, Collection<V>> asMap() {
    return delegate().asMap();
  }

  @Override
  public void clear() {
    delegate().clear();
  }

  @Override
  public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
    return delegate().containsEntry(key, value);
  }

  @Override

  @Override
  protected abstract Multimap<K, V> delegate();

  @Override
  public Map<K, Collection<V>> asMap() {
    return delegate().asMap();
  }

  @Override
  public void clear() {
    delegate().clear();
  }

  @Override
  public boolean containsEntry(@Nullable Object key, @Nullable Object value) {
    return delegate().containsEntry(key, value);
  }

  @Override

  @Override
  public boolean containsKey(@Nullable Object key) {
    Map<K, V> delegate = delegateOrNull();
    return (delegate != null) ? delegate.containsKey(key) : indexOf(key) != -1;
  }

  @Override
  public @Nullable V get(@Nullable Object key) {
    Map<K, V> delegate = delegateOrNull();
    if (delegate != null) {
      return delegate.get(key);
    }
    int index = indexOf(key);
    if (index == -1) {

        iterator.close();

        verify(delegate).close();
    }

    @Test
    @DisplayName("Close propagates exception")
    void closeException() throws CIFSException {
        when(delegate.hasNext()).thenReturn(false);
        doThrow(new CIFSException("Close failed")).when(delegate).close();

        TestIterator iterator = new TestIterator(null);

  @Override
  protected abstract ConcurrentMap<K, V> delegate();

  @CanIgnoreReturnValue
  @Override
  public @Nullable V putIfAbsent(K key, V value) {
    return delegate().putIfAbsent(key, value);
  }

  @CanIgnoreReturnValue
  @Override
  public boolean remove(@Nullable Object key, @Nullable Object value) {
    return delegate().remove(key, value);
  }

  @CanIgnoreReturnValue
  @Override