static class StrongKeyStrongValueEntry<K, V>
      extends AbstractStrongKeyEntry<K, V, StrongKeyStrongValueEntry<K, V>>
      implements StrongValueEntry<K, V, StrongKeyStrongValueEntry<K, V>> {
    private volatile @Nullable V value = null;

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

    @Override