for k, v := range headers.GetRequest().GetSet() {
		if !isAuthorityHeader(k) {
			continue
		}
		if current != "" {
			return fmt.Errorf("authority header cannot be set multiple times: have %q, attempting to set %q", current, v)
		}
		current = v
	}
	for k, v := range headers.GetRequest().GetAdd() {
		if !isAuthorityHeader(k) {
			continue
		}
		if current != "" {

func isInternalHeader(headerKey string) bool {
	return strings.HasPrefix(headerKey, ":") || strings.EqualFold(headerKey, "host")
}

// isAuthorityHeader returns true if a header refers to the authority header
func isAuthorityHeader(headerKey string) bool {
	return strings.EqualFold(headerKey, ":authority") || strings.EqualFold(headerKey, "host")
}

func dropInternal(keys []string) []string {

func ValidateHTTPHeaderWithAuthorityOperationName(name string) error {
	if name == "" {
		return fmt.Errorf("header name cannot be empty")
	}
	// Authority header is validated later
	if isInternalHeader(name) && !isAuthorityHeader(name) {
		return fmt.Errorf(`invalid header %q: header cannot have ":" prefix`, name)
	}
	return nil
}