The RadiobuttonGroup Widget for example has the property “selectedKey”
Due to its nature it does not provide any output to selectedKey, nor can anyone store a variable at its place and modify the widget with it.
the ‘selectedKey’ property was introduced as a custom property by us to enable app builders to handle RadioButtonGroups in a similar fashion to e.g. a Select widget. This would be the reason why you cannot find said property in the UI5’s official API reference. If you want to preselect and modify the widget using a variable binding, my suggestion would be to use the native ‘selectedIndex’ property of the RadioButtonGroup instead.
If you encounter a bug related to the behaviour of ‘selectedKey’ for RadioButtonGroup when bound to a variable, please raise a ticket for the same so we can find a possible fix for it: Support
