provider/domain_filter.go
func NewDomainFilter(domainFilters []string) DomainFilter {
	filters := make([]string, len(domainFilters))

	// user can define filter domains either with trailing dot or without, we remove all trailing periods from
	// the internal representation
	for i, domain := range domainFilters {
		filters[i] = strings.TrimSuffix(strings.TrimSpace(domain), ".")
	}

	return DomainFilter{filters}
}
func NewDomainFilter(domainFilters []string) DomainFilter {
	filters := make([]string, len(domainFilters))

	// user can define filter domains either with trailing dot or without, we remove all trailing periods from
	// the internal representation
	for i, domain := range domainFilters {
		filters[i] = strings.TrimSuffix(strings.TrimSpace(domain), ".")
	}

	return DomainFilter{filters}
}
// NewDomainFilter returns a new DomainFilter given a comma separated list of domains