Warning during dynamic object creation

import QtQuick 2.0
import QtQuick.Controls 1.2

ApplicationWindow {
    id: root
    width: 600
    height: 600
    visible: true
    
    QtObject {
        id: parentObject
    }
    
    Component {
        id: childObjectComponent
        QtObject {}
    }
    
    Component.onCompleted: {
        childObjectComponent.createObject(parentObject, {})
    }
}