func (r Rule) validateExpiration() error {
	return r.Expiration.Validate()
}

func (r Rule) validateNoncurrentExpiration() error {
	return r.NoncurrentVersionExpiration.Validate()
}

func (r Rule) validatePrefixAndFilter() error {
	// In the now deprecated PutBucketLifecycle API, Rule had a mandatory Prefix element and there existed no Filter field.
	// See https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutBucketLifecycle.html