@GwtIncompatible // To be supported
  MapMaker keyEquivalence(Equivalence<Object> equivalence) {
    checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);
    keyEquivalence = checkNotNull(equivalence);
    this.useCustomMap = true;
    return this;
  }

  Equivalence<Object> getKeyEquivalence() {
    return MoreObjects.firstNonNull(keyEquivalence, getKeyStrength().defaultEquivalence());
  }

  @GwtIncompatible // To be supported
  MapMaker keyEquivalence(Equivalence<Object> equivalence) {
    checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);
    keyEquivalence = checkNotNull(equivalence);
    this.useCustomMap = true;
    return this;
  }

  Equivalence<Object> getKeyEquivalence() {
    return MoreObjects.firstNonNull(keyEquivalence, getKeyStrength().defaultEquivalence());
  }

    final Strength valueStrength;
    final Equivalence<Object> keyEquivalence;
    final Equivalence<Object> valueEquivalence;
    final int concurrencyLevel;

    transient ConcurrentMap<K, V> delegate;

    AbstractSerializationProxy(
        Strength keyStrength,
        Strength valueStrength,
        Equivalence<Object> keyEquivalence,
        Equivalence<Object> valueEquivalence,

  }

  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");

  @CanIgnoreReturnValue
  CacheBuilder<K, V> keyEquivalence(Equivalence<Object> equivalence) {
    checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);
    keyEquivalence = checkNotNull(equivalence);
    return this;
  }

  Equivalence<Object> getKeyEquivalence() {
    return MoreObjects.firstNonNull(keyEquivalence, getKeyStrength().defaultEquivalence());
  }

  /**

    final Strength valueStrength;
    final Equivalence<Object> keyEquivalence;
    final Equivalence<Object> valueEquivalence;
    final int concurrencyLevel;

    transient ConcurrentMap<K, V> delegate;

    AbstractSerializationProxy(
        Strength keyStrength,
        Strength valueStrength,
        Equivalence<Object> keyEquivalence,
        Equivalence<Object> valueEquivalence,

  @CanIgnoreReturnValue
  CacheBuilder<K, V> keyEquivalence(Equivalence<Object> equivalence) {
    checkState(keyEquivalence == null, "key equivalence was already set to %s", keyEquivalence);
    keyEquivalence = checkNotNull(equivalence);
    return this;
  }

  Equivalence<Object> getKeyEquivalence() {
    return MoreObjects.firstNonNull(keyEquivalence, getKeyStrength().defaultEquivalence());
  }

  /**

        Ticker ticker,
        CacheLoader<? super K, V> loader) {
      this.keyStrength = keyStrength;
      this.valueStrength = valueStrength;
      this.keyEquivalence = keyEquivalence;
      this.valueEquivalence = valueEquivalence;
      this.expireAfterWriteNanos = expireAfterWriteNanos;
      this.expireAfterAccessNanos = expireAfterAccessNanos;
      this.maxWeight = maxWeight;

    assertWithMessage("refreshNanos").that(actual.refreshNanos).isEqualTo(expected.refreshNanos);
    assertWithMessage("keyEquivalence")
        .that(actual.keyEquivalence)
        .isEqualTo(expected.keyEquivalence);
    assertWithMessage("keyStrength").that(actual.keyStrength).isEqualTo(expected.keyStrength);
    assertWithMessage("removalListener")
        .that(actual.removalListener)

        Ticker ticker,
        CacheLoader<? super K, V> loader) {
      this.keyStrength = keyStrength;
      this.valueStrength = valueStrength;
      this.keyEquivalence = keyEquivalence;
      this.valueEquivalence = valueEquivalence;
      this.expireAfterWriteNanos = expireAfterWriteNanos;
      this.expireAfterAccessNanos = expireAfterAccessNanos;
      this.maxWeight = maxWeight;