entryOne.setValueReference(map.newValueReference(entryOne, valueOne, 1));

      Object keyTwo = new Object();
      Object valueTwo = new Object();
      int hashTwo = map.hash(keyTwo);
      ReferenceEntry<Object, Object> entryTwo = map.newEntry(keyTwo, hashTwo, entryOne);
      entryTwo.setValueReference(map.newValueReference(entryTwo, valueTwo, 1));

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

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

  /** Returns the next entry in the chain. */
  @Nullable ReferenceEntry<K, V> getNext();

  /** Returns the entry's hash. */
  int getHash();