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

  Equivalence<Object> getValueEquivalence() {
    return MoreObjects.firstNonNull(valueEquivalence, getValueStrength().defaultEquivalence());
  }

    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,
        int concurrencyLevel,
        ConcurrentMap<K, V> delegate) {