/** Concrete implementation of {@link InternalEntry} for strong keys and {@link Dummy} values. */
  private static class StrongKeyDummyValueEntry<K>
      extends AbstractStrongKeyEntry<K, Dummy, StrongKeyDummyValueEntry<K>>
      implements StrongValueEntry<K, Dummy, StrongKeyDummyValueEntry<K>> {

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

    @Override
    public final Dummy getValue() {