CallbackProperty for entity.position in typescript

I use the following code

var windowPosition = new Cesium.Cartesian2(viewer.container.clientWidth / 2, viewer.container.clientHeight / 2);
		  var pickPosition =;

		  // var position = Cesium.Cartesian3.fromDegrees(11.35463381710764, 49.063505);
		  var position = pickPosition;
		  var positionCBP = function(){
			return position;
		  myTarget = viewer.entities.add({
			name : 'Target on surface',
			position: new Cesium.CallbackProperty(positionCBP, false),
			billboard: {
				 image: 'Images/target.png',
				 heightReference: Cesium.HeightReference.NONE

for dynamically picking. there also exists an example as sandcastle Cesium Sandcastle

But in typescript I get errors similar:

TS2322: Type ‘CallbackProperty’ is not assignable to type ‘Cartesian3 | PositionProperty | undefined’.
Type ‘CallbackProperty’ is missing the following properties from type ‘PositionProperty’: referenceFrame, getValueInReferenceFrame

In Various TS issues/questions · Issue #8927 · CesiumGS/cesium · GitHub Matthew talks about this for Cesium 1.71 but I didn’t found it. There is also CallbackProperty and positions · Issue #8944 · CesiumGS/cesium · GitHub concerning this topic.

Is there a solution ?