code: func (m *ExternalCAOption) String() string {
  	externalCAs := []string{}
  	for _, externalCA := range m.values {
  		repr := fmt.Sprintf("%s: %s", externalCA.Protocol, externalCA.URL)
  		externalCAs = append(externalCAs, repr)
  	}
  	return strings.Join(externalCAs, ", ")
  }
docs: // String returns a string repr of this option.