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

    private StrongKeyWeakValueEntry(K key, int hash) {
      super(key, hash);
    }

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

    private StrongKeyWeakValueEntry(K key, int hash) {
      super(key, hash);
    }