@Override
      @ParametricNullness
      V output(@ParametricNullness K key, @ParametricNullness V value) {
        return value;
      }
    };
  }

  @Override
  Spliterator<V> valueSpliterator() {
    return CollectSpliterators.flatMap(
        map.values().spliterator(), Collection::spliterator, Spliterator.SIZED, size());
  }

  /*

      @Override
      protected @Nullable V get(int index) {
        return getValue(index);
      }
    };
  }

  @Override
  Spliterator<@Nullable V> valuesSpliterator() {
    return CollectSpliterators.<@Nullable V>indexed(size(), Spliterator.ORDERED, this::getValue);
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;