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

  /**
   * Specifies that each entry should be automatically removed from the cache once a fixed duration
   * has elapsed after the entry's creation, or the most recent replacement of its value.
   *
   * <p>When {@code duration} is zero, this method hands off to {@link #maximumSize(long)

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

  /**
   * Specifies that each entry should be automatically removed from the cache once a fixed duration
   * has elapsed after the entry's creation, or the most recent replacement of its value.
   *
   * <p>When {@code duration} is zero, this method hands off to {@link #maximumSize(long)