* response cache won't be used.
     */
    private fun hasConditions(request: Request): Boolean =
      request.header("If-Modified-Since") != null || request.header("If-None-Match") != null
  }

  companion object {
    /** Returns true if [response] can be stored to later serve another request. */
    fun isCacheable(
      response: Response,
      request: Request,
    ): Boolean {