SpinBox does not respect its focusPolicy

// Main.qml
import QtQuick 2.14
import QtQuick.Window 2.14
import QtQuick.Layouts 1.14
import QtQuick.Controls 2.14

Window {
    id: mainWindow

    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")

    function getFocusPolicy(intValue) {
        switch (intValue) {
        case Qt.TabFocus:
            return "TabFocus";
        case Qt.ClickFocus:
            return "ClickFocus";
        case Qt.StrongFocus:
            return "StrongFocus";
        case Qt.WheelFocus:
            return "WheelFocus";
        case Qt.NoFocus:
            return "NoFocus";
        }
    }

    ColumnLayout {
        TestSpinBox {}
        TestButton { }

        TestSpinBox { focusPolicy: Qt.StrongFocus }
        TestButton { focusPolicy: Qt.StrongFocus }

        TestSpinBox { focusPolicy: Qt.ClickFocus }
        TestButton { focusPolicy: Qt.ClickFocus }

        TestSpinBox { focusPolicy: Qt.TabFocus }
        TestButton { focusPolicy: Qt.TabFocus }

        TestSpinBox { focusPolicy: Qt.NoFocus }
        TestButton { focusPolicy: Qt.NoFocus }

    }
}

// TestButton.qml
import QtQuick 2.14
import QtQuick.Controls 2.14

Button {
    id: testButton

    implicitHeight: 24
    implicitWidth: 120

    background: Rectangle {
        color: testButton.activeFocus ? "green" : "grey"
    }

    text: mainWindow.getFocusPolicy(testButton.focusPolicy)
}

// TestSpinBox
import QtQuick 2.14
import QtQuick.Layouts 1.14
import QtQuick.Controls 2.14

RowLayout {
    id: testSpinBox

    property int focusPolicy: 0

    Text {
        text: mainWindow.getFocusPolicy(spinBox.focusPolicy)
    }

    SpinBox { id: spinBox; focusPolicy: testSpinBox.focusPolicy }
}