+kubebuilder:validation:Required marker not working

[parthyadav3105]

What happened
On using +kubebuilder:validation:Required marker on fields(or packages both) does not adds that field to required list in the generated crd output.

Example:

type ImageSpec struct {
	// +kubebuilder:validation:Required
	Foo string `json:"foo,omitempty"`
}

output crd:

---
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  annotations:
    controller-gen.kubebuilder.io/version: v0.4.1
  creationTimestamp: null
  name: images.hello.io.kupenstack.io
spec:
  group: hello.io.kupenstack.io
  names:
    kind: Image
    listKind: ImageList
    plural: images
    singular: image
  scope: Namespaced
  versions:
  - name: v1alpha1
    schema:
      openAPIV3Schema:
        description: Image is the Schema for the images API
        properties:
          apiVersion:
            type: string
          kind:
            type: string
          metadata:
            type: object
          spec:
            description: ImageSpec defines the desired state of Image
            properties:
              foo:
                type: string
            type: object
          status:
            description: ImageStatus defines the observed state of Image
            type: object
        type: object
    served: true
    storage: true
    subresources:
      status: {}
status:
  acceptedNames:
    kind: ""
    plural: ""
  conditions: []
  storedVersions: []

What you expected to happen:
According to reference documentation foo field in above crd should be a required field as shown bellow:

---
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  annotations:
    controller-gen.kubebuilder.io/version: v0.4.1
  creationTimestamp: null
  name: images.hello.io.kupenstack.io
spec:
  group: hello.io.kupenstack.io
  names:
    kind: Image
    listKind: ImageList
    plural: images
    singular: image
  scope: Namespaced
  versions:
  - name: v1alpha1
    schema:
      openAPIV3Schema:
        description: Image is the Schema for the images API
        properties:
          apiVersion:
            type: string
          kind:
            type: string
          metadata:
            type: object
          spec:
            description: ImageSpec defines the desired state of Image
            properties:
              foo:
                type: string
            type: object
            required:
            - foo
          status:
            description: ImageStatus defines the observed state of Image
            type: object
        type: object
        required:
        - spec
    served: true
    storage: true
    subresources:
      status: {}
status:
  acceptedNames:
    kind: ""
    plural: ""
  conditions: []
  storedVersions: []

Environment:
Controller-gen version: v0.4.1
Kubernetes version: Server Version: v1.21.4

[parthyadav3105]

Update:
The omitempty tag in Foo string `json:"foo,omitempty"` had more precedence than the kubebuilder marker +kubebuilder:validation:Required therefore making the resultant generated crd field to be optional.

The +kubebuilder:validation:Required marker does works as desired when omitempty is not used.

I am not able to recall if docs(https://book.kubebuilder.io) mentions it, but I hope it does.

With that I mark this issue to be closed.