Fires before the value of the controls in the UX are persisted to Local Storage. The purpose of this event is to allow you to capture arbitrary data and store it in local storage with the variable values. Your code can set the 'userData' property in the 'e' object. The value in 'userData' will be available when the 'onRestoreVariablesFromLocalStorage' event is fired. The 'controlName' property is the control that triggered the event.
controlName, controlType, sourceElement, userData