How to patch Cluster with EnvoyPatchPolicy

Description: An example would be nice to determine how to modify cluster config in EnvoyPatchPolicy

apiVersion: gateway.networking.k8s.io/v1
kind: GatewayClass
metadata:
  name: eg
spec:
  controllerName: gateway.envoyproxy.io/gatewayclass-controller
---
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: eg
  namespace: envoy-poc
spec:
  gatewayClassName: eg
  listeners:
  - name: http
    port: 80
    protocol: HTTP
    allowedRoutes:
      namespaces:
        from: Same
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: server-route
  namespace: envoy-poc
spec:
  parentRefs:
  - name: eg
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /
    backendRefs:
    - name: server
      port: 8080
---
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: EnvoyPatchPolicy
metadata:
  name: server-route-client-wrr
  namespace: envoy-poc
spec:
  type: JSONPatch
  targetRef:
    group: gateway.networking.k8s.io
    kind: GatewayClass
    name: eg
  jsonPatches:
  - type: type.googleapis.com/envoy.config.cluster.v3.Cluster
    name: httproute/envoy-poc/server-route/rule/0
    operation:
      op: add
      path: /load_balancing_policy
      value:
        policies:
        - typed_extension_config:
            name: envoy.load_balancing_policies.client_side_weighted_round_robin
            typed_config:
              "@type": type.googleapis.com/envoy.extensions.load_balancing_policies.client_side_weighted_round_robin.v3.ClientSideWeightedRoundRobin

I am doing the following but the patch is not working