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

  Strength getValueStrength() {
    return MoreObjects.firstNonNull(valueStrength, Strength.STRONG);
  }

  /**