Prevent Updates to Project in CEL expressions

apiVersion: kyverno.io/v1
kind: ClusterPolicy
metadata:
  name: application-prevent-updates-project
  annotations:
    policies.kyverno.io/title: Prevent Updates to Project in CEL expressions
    policies.kyverno.io/category: Argo in CEL
    policies.kyverno.io/severity: medium
    kyverno.io/kyverno-version: 1.12.0
    kyverno.io/kubernetes-version: 1.26-1.27
    policies.kyverno.io/subject: Application
    policies.kyverno.io/description: This policy prevents updates to the project field after an Application is created.
spec:
  validationFailureAction: Audit
  background: true
  rules:
    - name: project-updates
      match:
        any:
          - resources:
              kinds:
                - Application
      celPreconditions:
        - name: operation-should-be-update
          expression: request.operation == 'UPDATE'
      validate:
        cel:
          expressions:
            - expression: object.spec.project == oldObject.spec.project
              message: The spec.project cannot be changed once the Application is created.