Object.getOwnPropertyNames() doesn't work with attached properties

import QtQuick 2.12
import QtQuick.Controls 2.12
import QtQuick.Controls.Material 2.12

ApplicationWindow {
    id: root
    visible: true
    Component.onCompleted: console.log(Material, "has properties", Object.getOwnPropertyNames(root.Material))
}

$ qml material-props.qml 
[     0.000 D] qml onCompleted - QQuickMaterialStyle(0x5632cf078980) has properties []