Popup without explicit closePolicy closes App on Android BACK key

import QtQuick 2.7
import QtQuick.Controls 2.1
import QtQuick.Layouts 1.3
import QtQuick.Controls.Material 2.1

ApplicationWindow {
    id: window
    width: 640
    height: 480
    visible: true

    Page {
        id: thePage
        anchors.fill: parent

        Label {
            id: theLabel
            text: "Close Policy Test"
            anchors.centerIn: parent
        }

        Button {
            anchors.top: theLabel.bottom
            text: "Popup BACK KEy Test"
            onClicked: {
                thePopup.open()
            }
        }


        Popup {
            id: thePopup
            // closePolicy: Popup.CloseOnPressOutside
            width: 200
            height: 200
            Label {
                text: "Press BACK Key"
            }
        }

        Keys.onBackPressed: {
            event.accepted = true
            theLabel.text = "BACK KEY consumed"
        }


    } // page
}