}

  @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);