*
     * **This feature is not supported on Android API levels less than 24.** Prior releases lacked
     * a mechanism to trust some hosts and not others.
     *
     * @param hostname the exact hostname from the URL for insecure connections.
     */
    fun addInsecureHost(hostname: String) =
      apply {
        insecureHosts += hostname
      }

    fun build(): HandshakeCertificates {