* #UNSET_WEAK_VALUE_REFERENCE} below.
   */
  static final class DummyInternalEntry
      implements InternalEntry<Object, Object, DummyInternalEntry> {
    private DummyInternalEntry() {
      throw new AssertionError();
    }

    @Override
    public DummyInternalEntry getNext() {
      throw new AssertionError();
    }

    @Override
    public int getHash() {