private static class WeakKeyWeakValueEntry<K, V>
      extends AbstractWeakKeyEntry<K, V, WeakKeyWeakValueEntry<K, V>>
      implements WeakValueEntry<K, V, WeakKeyWeakValueEntry<K, V>> {
    private volatile WeakValueReference<K, V, WeakKeyWeakValueEntry<K, V>> valueReference =
        unsetWeakValueReference();

    WeakKeyWeakValueEntry(ReferenceQueue<K> queue, K key, int hash) {