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