@SuppressWarnings("serial") static final class KeyIterator<K,V> extends Traverser<K,V,Object>
            implements Spliterator<K>, Enumeration<K> {
        KeyIterator(ConcurrentHashMapV8<K, V> map) { super(map); }
        KeyIterator(Traverser<K,V,Object> it) {
            super(it);