Strength keyStrength() {
    return entryHelper.keyStrength();
  }

  @VisibleForTesting
  Strength valueStrength() {
    return entryHelper.valueStrength();
  }

  @VisibleForTesting
  Equivalence<Object> valueEquivalence() {
    return entryHelper.valueStrength().defaultEquivalence();
  }

  // ConcurrentMap methods

  @Override
  public boolean isEmpty() {
    /*

  @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);
  }

  /**