}
    }

    protected <K, V> Map<K, V> map(Map<K, Supplier<V>> map) {
        return new WrappingMap<>(map, Supplier::get);
    }

    private static class WrappingMap<K, V, T> extends AbstractMap<K, V> {

        private final Map<K, T> delegate;
        private final Function<T, V> mapper;

        WrappingMap(Map<K, T> delegate, Function<T, V> mapper) {
            this.delegate = delegate;