Google Maps for AngularJS Makers Cluseter events(v1.2.1)

<script src="https://maps.googleapis.com/maps/api/js?v=3.exp&key=xxxxxxxxxxxxxxxxxx&sensor=false"></script>
<script type='text/javascript' src='http://www.example.com/wp/wp-content/themes/ang/js/lodash.underscore.min.js'></script>
<script type='text/javascript' src='http://www.example.com/wp/wp-content/themes/ang/js/angular-google-maps.min.js'></script>
<script type='text/javascript' src='http://www.example.com/wp/wp-content/themes/ang/js/app.js'></script>
<div ng-controller="MyCtrl">
  <div class="row">
    <div class="col-sm-12">
      <google-map 
        id="map-canvas"
        center="map.center"
        zoom="map.zoom"
        draggable="true"
        options="map.options"
      >
        <markers models="map.Markers" coords="'self'" click="'onClicked'"
               doCluster="map.ClusterMarkers" clusterOptions="map.clusterOptions" clusterEvents="clusterEvents">
          <windows show="'showWindow'" closeClick="'closeClick'" ng-cloak>
            <p ng-non-bindable>This is an info window at {  { latitude | number:4 }}, {  { longitude | number:4 }}!</p>
          </windows>  
        </markers>
      </google-map>
    </div>
  </div>
</div>

var mapApp = angular.module('googleMapApp', ['google-maps','ui.bootstrap']);

mapApp.controller("MyCtrl", function ($scope) {
  angular.extend($scope, {
    map: {
      center: {
        latitude: 35.681382,
        longitude: 139.766084
      },
      options: {
        maxZoom: 20,
        minZoom: 3
      },
      zoom: 15,
      Markers: [
        {
          latitude: 35.681,
          longitude: 139.766,
          id:1
        },
        {
          latitude: 35.683,
          longitude: 139.766,
          id:2
        },
        {
          latitude: 35.679,
          longitude: 139.765,
          id:3
        },
        {
          latitude: 35.682,
          longitude: 139.769,
          id:4
        }
      ],
      ClusterMarkers: true,
      clusterOptions: {
          title: 'Cluster Markers', 
          gridSize: 60, 
          ignoreHidden: true, 
          minimumClusterSize: 2
      }
    }
  });
  $scope.clusterEvents = {
    click: function (cluster, clusterModels) {
      alert("Cluster Models:" + JSON.stringify(clusterModels));
    }
  };
  angular.forEach($scope.map.markers, function (marker) {
      marker.closeClick = function () {
          marker.showWindow = false;
          $scope.$apply();
      };
      marker.onClicked = function () {
          marker.showWindow = true;
          $scope.$apply();
      };
  });
});