@Override
  protected abstract SortedSet<E> delegate();

  @Override
  public @Nullable Comparator<? super E> comparator() {
    return delegate().comparator();
  }

  @Override
  @ParametricNullness
  public E first() {
    return delegate().first();
  }

  @Override
  public SortedSet<E> headSet(@ParametricNullness E toElement) {
    return delegate().headSet(toElement);
  }

  @Override

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

  @Override
  public int size() {
    return delegate().size();
  }

  @Override
  public boolean isEmpty() {
    return delegate().isEmpty();
  }

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

  @Override
  public void clear() {

  }

  private final Map<Class<? extends @NonNull B>, B> delegate;

  private MutableClassToInstanceMap(Map<Class<? extends @NonNull B>, B> delegate) {
    this.delegate = checkNotNull(delegate);
  }

  @Override
  protected Map<Class<? extends @NonNull B>, B> delegate() {
    return delegate;
  }

  /**

  }

  @Override
  public final boolean isRunning() {
    return delegate.isRunning();
  }

  @Override
  public final State state() {
    return delegate.state();
  }

  /**
   * @since 13.0
   */
  @Override
  public final void addListener(Listener listener, Executor executor) {
    delegate.addListener(listener, executor);
  }

  /**
   * @since 14.0
   */

  @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

  @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

    private final Callable<T> delegate;

    WrappedCallable(Callable<T> delegate) {
      this.delegate = delegate;
    }

    @Override
    public T call() throws Exception {
      return delegate.call();
    }
  }

  private static final class WrappedRunnable implements Runnable {
    private final Runnable delegate;

    WrappedRunnable(Runnable delegate) {
      this.delegate = delegate;
    }

    return delegate().remove(element, occurrences);
  }

  @Override
  public Set<E> elementSet() {
    return delegate().elementSet();
  }

  @Override
  public Set<Entry<E>> entrySet() {
    return delegate().entrySet();
  }

  @Override
  public boolean equals(@Nullable Object object) {
    return object == this || delegate().equals(object);
  }

  @Override

        .addEqualityGroup(set2, wrap(set2))
        .testEquals();
  }

  private static <T> SortedSet<T> wrap(SortedSet<T> delegate) {
    return new ForwardingSortedSet<T>() {
      @Override
      protected SortedSet<T> delegate() {
        return delegate;
      }
    };
  }

        .addEqualityGroup(set2, wrap(set2))
        .testEquals();
  }

  private static <T> Set<T> wrap(Set<T> delegate) {
    return new ForwardingSet<T>() {
      @Override
      protected Set<T> delegate() {
        return delegate;
      }
    };
  }