Using attached ScrollBar from namespace

[thesourcehim]

In my form I need both Controls 1.4 and Controls 2.0, so I put Controls 2.0 into namespace:
import QtQuick.Controls 2.0 as Controls2

But now I can't attach scrollbars to Flickable, both of the following lines are invalid:
ScrollBar.horizontal: Controls2.ScrollBar { id: hbar } //Non-existent attached object
Controls2.ScrollBar.horizontal: Controls2.ScrollBar { id: hbar} //Can not assign object to read only list

Can I attach scrollbars when they are in namespace?