custom envoy filter max body size

apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: limit-request-default
  namespace: istio-system
spec:
  #  If the EnvoyFilter is present in the config root namespace, it will be applied to all applicable workloads in any namespace.
  # It looks like this filter was being applied to all gateways as it wasn't a valid selector
  #workloadSelector:
  #  labels:
  #    istio: ingressgateway
  configPatches:
  - applyTo: HTTP_FILTER
    match:
      context: GATEWAY
      listener:
        filterChain:
          filter:
            name: envoy.http_connection_manager
    patch:
      operation: INSERT_BEFORE
      value:
        name: envoy.buffer
        typed_config:
          '@type': type.googleapis.com/udpa.type.v1.TypedStruct
          value:
            maxRequestBytes: 12582912  # 12 MB