// defaultBackend is the backend that should handle requests that don't
	// match any rule. If Rules are not specified, DefaultBackend must be specified.
	// If DefaultBackend is not set, the handling of requests that do not match any
	// of the rules will be up to the Ingress controller.
	// +optional
	DefaultBackend *IngressBackend `json:"defaultBackend,omitempty" protobuf:"bytes,1,opt,name=defaultBackend"`

	allErrs := field.ErrorList{}
	if len(spec.Rules) == 0 && spec.DefaultBackend == nil {
		errMsg := fmt.Sprintf("either `%s` or `rules` must be specified", "defaultBackend")
		allErrs = append(allErrs, field.Invalid(fldPath, spec.Rules, errMsg))
	}
	if spec.DefaultBackend != nil {
		allErrs = append(allErrs, validateIngressBackend(spec.DefaultBackend, fldPath.Child("defaultBackend"), opts)...)
	}
	if len(spec.Rules) > 0 {

  optional string ingressClassName = 4;

  // defaultBackend is the backend that should handle requests that don't
  // match any rule. If Rules are not specified, DefaultBackend must be specified.
  // If DefaultBackend is not set, the handling of requests that do not match any
  // of the rules will be up to the Ingress controller.
  // +optional
  optional IngressBackend defaultBackend = 1;

  optional string ingressClassName = 4;

  // defaultBackend is the backend that should handle requests that don't
  // match any rule. If Rules are not specified, DefaultBackend must be specified.
  // If DefaultBackend is not set, the handling of requests that do not match any
  // of the rules will be up to the Ingress controller.
  // +optional
  optional IngressBackend defaultBackend = 1;