testIdentityKeyEquality(WEAK);
  }

  private void testIdentityKeyEquality(MapMakerInternalMap.Strength keyStrength) {

    ConcurrentMap<String, AtomicInteger> map =
        new MapMaker().setKeyStrength(keyStrength).keyEquivalence(Equivalence.identity()).makeMap();

    ConcurrentHashMultiset<String> multiset = ConcurrentHashMultiset.create(map);

    String s1 = new String("a");
    String s2 = new String("a");

   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);
    keyStrength = checkNotNull(strength);
    return this;
  }

   */
  @GwtIncompatible // java.lang.ref.WeakReference
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> weakKeys() {
    return setKeyStrength(Strength.WEAK);
  }

  @CanIgnoreReturnValue
  CacheBuilder<K, V> setKeyStrength(Strength strength) {
    checkState(keyStrength == null, "Key strength was already set to %s", keyStrength);
    keyStrength = checkNotNull(strength);
    return this;
  }