the background is that, My app is written with Qt5.13, the Combobox does not have property "currentValue" in this version, So I defined one. 

But When I upgrade to Qt5.15, this property is added, So the app will crash with error"Cannot override FINAL property".

I don't want to modify my source code because the property "currentValue" is used in many places. I tried to write like this. but failed. 

// code placeholder
import QtQuick.Controls 2.13 as QC13
QC13.ComboBox {
property var currentValue: ""
}

 The app will still crash , the error is same. 

It seems that, If I use Qt5.15 to build my app, I can not force to use controls of 5.13 , right?