code: function (args, propertyName) {
                  if (this._cfg) {
                      this.onbind(propertyName, this._transform(this._cfg.bind[propertyName].transform, args.newValue, "toWidget"), args.oldValue);
                  }
              }
docs: Called when a change occurs for a value with binding.
  @protected
  @param {Object} args details about what changed
  @param {String} propertyName key of the binding configuration that registered this callback
  @override