}

    private fun validity(): Validity {
      val notBefore = if (notBefore != -1L) notBefore else System.currentTimeMillis()
      val notAfter = if (notAfter != -1L) notAfter else notBefore + DEFAULT_DURATION_MILLIS
      return Validity(
        notBefore = notBefore,
        notAfter = notAfter,
      )
    }

    private fun extensions(): MutableList<Extension> {
      val result = mutableListOf<Extension>()