An event handler function to execute when a property is changed. Functions
will be passed an event object including the following properties:
propertyDescriptor [type: dundas.PropertyDescriptor] - The property descriptor defining the property that was changed.
objectDescriptor [type: dundas.controls.ObjectDescriptor] - The object descriptor to which the property descriptor was added.
oldValue [type: Object, mayBeNull: true] - The previous value of the property.
newValue [type: Object, mayBeNull: true] - The new value of the property.
eventData [type: Object]
changedPropertyId [type: String] - The ID of the property descriptor that was changed.
beforeState [type: String] - The adapter stringified as JSON before the property change.