request.newBuilder()
          .headers(conditionalRequestHeaders.build())
          .build()
      return CacheStrategy(conditionalRequest, cacheResponse)
    }

    /**
     * Returns the number of milliseconds that the response was fresh for, starting from the served
     * date.
     */
    private fun computeFreshnessLifetime(): Long {
      val responseCaching = cacheResponse!!.cacheControl