code: function (propertyName, newValue, oldValue) {
              if (propertyName === 'currentValue') {
                  this.__setCurrentValue(newValue);
              } else if (propertyName === 'label' && this.showLabel) {
                  this.__setLabel(newValue);
              } else if (propertyName === 'maxValue') {
                  this._cfg.maxValue = newValue;
                  this._checkCfgConsistency();
              } else {
                  this.$Widget._onBoundPropertyChange.call(this, propertyName, newValue, oldValue);
              }
  
          }
docs: Internal method called when one of the model property that the widget is bound to has changed Must be
  overridden by sub-classes defining bindable properties
  @param {String} propertyName The property name
  @param {Object} newValue The new value
  @param {Object} oldValue The old property value
  @protected