this.expireAfterWriteNanos = unit.toNanos(duration);
    return this;
  }

  @SuppressWarnings("GoodTime") // nanos internally, should be Duration
  long getExpireAfterWriteNanos() {
    return (expireAfterWriteNanos == UNSET_INT) ? DEFAULT_EXPIRATION_NANOS : expireAfterWriteNanos;
  }

  /**