code: func ValidateConditionalService(service, oldService *api.Service) field.ErrorList {
  	var errs field.ErrorList
  	// If the SCTPSupport feature is disabled, and the old object isn't using the SCTP feature, prevent the new object from using it
  	if !utilfeature.DefaultFeatureGate.Enabled(features.SCTPSupport) && len(serviceSCTPFields(oldService)) == 0 {
  		for _, f := range serviceSCTPFields(service) {
  			errs = append(errs, field.NotSupported(f, api.ProtocolSCTP, []string{string(api.ProtocolTCP), string(api.ProtocolUDP)}))
  		}
  	}
  	return errs
  }
docs: // ValidateConditionalService validates conditionally valid fields.