PodDisruptionBudget maxUnavailable Non-Zero

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: pdb-maxunavailable
  annotations:
    policies.kyverno.io/title: PodDisruptionBudget maxUnavailable Non-Zero
    policies.kyverno.io/category: Other
    kyverno.io/kyverno-version: 1.9.0
    kyverno.io/kubernetes-version: "1.24"
    policies.kyverno.io/subject: PodDisruptionBudget
    policies.kyverno.io/description: A PodDisruptionBudget which sets its maxUnavailable value to zero prevents all voluntary evictions including Node drains which may impact maintenance tasks. This policy enforces that if a PodDisruptionBudget specifies the maxUnavailable field it must be greater than zero.
spec:
  validationFailureAction: Audit
  background: false
  rules:
    - name: pdb-maxunavailable
      match:
        any:
          - resources:
              kinds:
                - PodDisruptionBudget
      validate:
        message: The value of maxUnavailable must be greater than zero.
        pattern:
          spec:
            "=(maxUnavailable)": ">0"