Does RequestMirrorPolicy support xDS? about envoy HOT 1 OPEN

// An optional boolean that specifies whether the clusters that the route
  // table refers to will be validated by the cluster manager. If set to true
  // and a route refers to a non-existent cluster, the route table will not
  // load. If set to false and a route refers to a non-existent cluster, the
  // route table will load and the router filter will return a 404 if the route
  // is selected at runtime. This setting defaults to true if the route table
  // is statically defined via the :ref:`route_config
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.route_config>`
  // option. This setting default to false if the route table is loaded dynamically via the
  // :ref:`rds
  // <envoy_v3_api_field_extensions.filters.network.http_connection_manager.v3.HttpConnectionManager.rds>`
  // option. Users may wish to override the default behavior in certain cases (for example when
  // using CDS with a static route table).
  google.protobuf.BoolValue validate_clusters = 7;