Authz Policy with wildcard presence match on claims with number values

Security
1

Hi,

I am trying to check the presence of an claim with type integer. In case I apply the authz policy as described below envoy does not find a matching policy. Without the wildcard “*” it is working. From what I understand from the Istio docs (Istio / Authorization Policy) any string field in the rule supports Exact, Prefix, Suffix and Presence match and configuring the when condition is a string field. So I would expect a working authz policy.

apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: jwt
  namespace: foo
spec:
  selector:
    matchLabels:
      app: httpbin
  action: ALLOW
  rules:
  - from:
    - source:
       requestPrincipals: ["someIssuer/dsfjfdf948487dkjsf"]
    when:
    - key: request.auth.claims[iat]
      values: ["*"]

Any ideas?