if (e.getValueReference().isActive()) {
                K key = e.getKey();
                V value = e.getValueReference().get();
                RemovalCause cause =
                    (key == null || value == null) ? RemovalCause.COLLECTED : RemovalCause.EXPLICIT;
                enqueueNotification(
                    key, e.getHash(), value, e.getValueReference().getWeight(), cause);
              }

      assertSame(valueOne, copyOne.getValueReference().get());
      assertConnected(map, copyOne, entryTwo);

      ReferenceEntry<Object, Object> copyTwo = map.copyEntry(entryTwo, copyOne);
      assertSame(keyTwo, copyTwo.getKey());
      assertEquals(hashTwo, copyTwo.getHash());
      assertSame(copyOne, copyTwo.getNext());
      assertSame(valueTwo, copyTwo.getValueReference().get());

      assertSame(valueOne, copyOne.getValueReference().get());
      assertConnected(map, copyOne, entryTwo);

      ReferenceEntry<Object, Object> copyTwo = map.copyEntry(entryTwo, copyOne);
      assertSame(keyTwo, copyTwo.getKey());
      assertEquals(hashTwo, copyTwo.getHash());
      assertSame(copyOne, copyTwo.getNext());
      assertSame(valueTwo, copyTwo.getValueReference().get());

 * </ul>
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
interface ReferenceEntry<K, V> {
  /** Returns the value reference from this entry. */
  @CheckForNull
  ValueReference<K, V> getValueReference();

  /** Sets the value reference for this entry. */
  void setValueReference(ValueReference<K, V> valueReference);

  /** Returns the next entry in the chain. */
  @CheckForNull

  interface WeakValueEntry<K, V, E extends InternalEntry<K, V, E>> extends InternalEntry<K, V, E> {
    /** Gets the weak value reference held by entry. */
    WeakValueReference<K, V, E> getValueReference();
  }

  @SuppressWarnings("unchecked") // impl never uses a parameter or returns any non-null value
  static <K, V, E extends InternalEntry<K, V, E>>
      WeakValueReference<K, V, E> unsetWeakValueReference() {

  interface WeakValueEntry<K, V, E extends InternalEntry<K, V, E>> extends InternalEntry<K, V, E> {
    /** Gets the weak value reference held by entry. */
    WeakValueReference<K, V, E> getValueReference();
  }

  @SuppressWarnings("unchecked") // impl never uses a parameter or returns any non-null value
  static <K, V, E extends InternalEntry<K, V, E>>
      WeakValueReference<K, V, E> unsetWeakValueReference() {

        WeakValueEntry<Object, Object, ?> entry =
            (WeakValueEntry<Object, Object, ?>) segment.getEntry(keyOne, hashOne);
        WeakValueReference<Object, Object, ?> valueReference = entry.getValueReference();

        @SuppressWarnings("unchecked")
        Reference<Object> reference = (Reference<Object>) valueReference;
        reference.enqueue();

        map.put(keyTwo, valueTwo);

        WeakValueEntry<Object, Object, ?> entry =
            (WeakValueEntry<Object, Object, ?>) segment.getEntry(keyOne, hashOne);
        WeakValueReference<Object, Object, ?> valueReference = entry.getValueReference();

        @SuppressWarnings("unchecked")
        Reference<Object> reference = (Reference<Object>) valueReference;
        reference.enqueue();

        map.put(keyTwo, valueTwo);