targetMap := make(map[string]struct{})
	priorityMap := make(map[string]struct{})
	var legacyArn bool
	for _, r := range c.Rules {
		if _, ok := targetMap[r.Destination.Bucket]; !ok {
			targetMap[r.Destination.Bucket] = struct{}{}
		}
		if err := r.Validate(bucket, sameTarget); err != nil {
			return err
		}
		if _, ok := priorityMap[strconv.Itoa(r.Priority)]; ok {
			return errReplicationUniquePriority
		}