Use ol.object.assign() instead of goog.object.extend()

src/ol/source/tilewmssource.js

@@ -12,6 +12,7 @@ goog.require('goog.uri.utils');
 goog.require('ol');
 goog.require('ol.TileCoord');
 goog.require('ol.extent');
+goog.require('ol.object');
 goog.require('ol.proj');
 goog.require('ol.size');
 goog.require('ol.source.TileImage');
@@ -33,7 +34,7 @@ ol.source.TileWMS = function(opt_options) {
 
   var options = opt_options || {};
 
-  var params = options.params !== undefined ? options.params : {};
+  var params = options.params || {};
 
   var transparent = goog.object.get(params, 'TRANSPARENT', true);
 
@@ -59,7 +60,7 @@ ol.source.TileWMS = function(opt_options) {
 
   /**
    * @private
-   * @type {Object}
+   * @type {!Object}
    */
   this.params_ = params;
 
@@ -161,7 +162,7 @@ ol.source.TileWMS.prototype.getGetFeatureInfoUrl = function(coordinate, resoluti
     'TRANSPARENT': true,
     'QUERY_LAYERS': this.params_['LAYERS']
   };
-  goog.object.extend(baseParams, this.params_, params);
+  ol.object.assign(baseParams, this.params_, params);
 
   var x = Math.floor((coordinate[0] - tileExtent[0]) / tileResolution);
   var y = Math.floor((tileExtent[3] - coordinate[1]) / tileResolution);
@@ -363,7 +364,7 @@ ol.source.TileWMS.prototype.fixedTileUrlFunction = function(tileCoord, pixelRati
     'FORMAT': 'image/png',
     'TRANSPARENT': true
   };
-  goog.object.extend(baseParams, this.params_);
+  ol.object.assign(baseParams, this.params_);
 
   return this.getRequestUrl_(tileCoord, tileSize, tileExtent,
       pixelRatio, projection, baseParams);
@@ -376,7 +377,7 @@ ol.source.TileWMS.prototype.fixedTileUrlFunction = function(tileCoord, pixelRati
  * @api stable
  */
 ol.source.TileWMS.prototype.updateParams = function(params) {
-  goog.object.extend(this.params_, params);
+  ol.object.assign(this.params_, params);
   this.resetCoordKeyPrefix_();
   this.resetParamsKey_();
   this.updateV13_();