JSON response for handler/denier

Is there a way for converting handler/denier’s responses to JSON response? Following denier produces “FAILED_PRECONDITION:handler.demo:Not allowed” But I need something like ‘{“message”: “Not Allowed”}’

apiVersion: "config.istio.io/v1alpha2"
kind: handler
metadata:
  name: handler
  namespace: demo
spec:
  compiledAdapter: denier
  params:
    status:
      code: 7
      message: Not allowed

Thank you.