in retry.go [115:121]
func (b *backOffStopIfTimeout) NextBackOff() time.Duration {
bkof := b.BackOff.NextBackOff()
if b.NotAfter.IsZero() || b.Now == nil || bkof == backoff.Stop || b.Now().After(b.NotAfter) {
return backoff.Stop
}
return bkof
}