How to properly use `oneOf` validation in Kubernetes CRDs

I'm trying to use oneOf to validate my Kubernetes CRDs and still couldn't make it work. I have the following CRD defined.

        openAPIV3Schema:
          type: object
          properties:
            spec:
              type: object
              properties:
                type:
                  type: string
                parameters:
                  type: array
                  items:
                    type: object
                    properties:
                      parameterName:
                        type: string
                      parameterValue:
                        type: string
                policySpec:
                  type: object
                  properties:
                    json:
                      x-kubernetes-preserve-unknown-fields: true
                      type: object
                      description: this is arbitrary JSON
                template:
                  type: string

I want to add oneOf validation to parameters, policySpec and template so the user can specify only one of those. I followed the docs related to oneOf but couldn't figure it out still.

xref for docs: https://kubernetes.io/docs/tasks/extend-kubernetes/custom-resources/custom-resource-definitions/#specifying-a-structural-schema

Also found a similar stackoverflow question with no proper answer : Properly using oneOf in a Kubernetes CRD OpenAPI schema

Any K8s folks out there who can help ? Thanks in advance