*  Upgrade: Build with Conscrypt 2.5.1.


## Version 4.8.1

_2020-08-06_

 *  Fix: Don't crash in `HeldCertificate.Builder` when creating certificates on older versions of
    Android, including Android 6. We were using a feature of `SimpleDateFormat` that wasn't
    available in those versions!


## Version 4.8.0

_2020-07-11_

    /** Age of the cached response. */
    private var ageSeconds = -1

    /**
     * Returns true if computeFreshnessLifetime used a heuristic. If we used a heuristic to serve a
     * cached response older than 24 hours, we are required to attach a warning.
     */
    private fun isFreshnessLifetimeHeuristic(): Boolean {
      return cacheResponse!!.cacheControl.maxAgeSeconds == -1 && expires == null
    }

    init {