"EEE, dd MMM yyyy HH:mm:ss zzz",
    // RFC 850, obsoleted by RFC 1036 with any TZ.
    "EEEE, dd-MMM-yy HH:mm:ss zzz",
    // ANSI C's asctime() format
    "EEE MMM d HH:mm:ss yyyy",
    // Alternative formats:
    "EEE, dd-MMM-yyyy HH:mm:ss z",
    "EEE, dd-MMM-yyyy HH-mm-ss z",
    "EEE, dd MMM yy HH:mm:ss z",
    "EEE dd-MMM-yyyy HH:mm:ss z",
    "EEE dd MMM yyyy HH:mm:ss z",
    "EEE dd-MMM-yyyy HH-mm-ss z",

  ): String? {
    return formatDate(Date(System.currentTimeMillis() + timeUnit.toMillis(delta)))
  }

  private fun formatDate(date: Date): String? {
    val rfc1123: DateFormat = SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss zzz", Locale.US)
    rfc1123.timeZone = TimeZone.getTimeZone("GMT")
    return rfc1123.format(date)
  }

                runningOnCi.get() -> "from current time because CI"
                else -> "from current date"
            }
        }

    private
    fun Date.withoutTime(): Date = SimpleDateFormat("yyyy-MM-dd").run {
        parse(format(this@withoutTime))
    }

abstract class BuildReceipt : DefaultTask() {
    companion object {
        private
        val timestampFormat = newSimpleDateFormatUTC("yyyyMMddHHmmssZ")

        private
        val isoTimestampFormat = newSimpleDateFormatUTC("yyyy-MM-dd HH:mm:ss z")

        private
        fun newSimpleDateFormatUTC(pattern: String) = SimpleDateFormat(pattern).apply {
            timeZone = TimeZone.getTimeZone("UTC")
        }