code: function (propertyName, newValue, oldValue) {
              if (propertyName === 'referenceDate') {
                  this.controller.setReferenceDate(newValue);
              } else {
                  this.$TextInput._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