Deafult ScrollBar does not disappear when overridden in ScrollView.

import QtQuick 2.15
import QtQuick.Controls 2.15
import QtQuick.Window 2.15

Window {
    width: 640
    height: 480
    visible: true

    ScrollView {
        anchors.centerIn: parent

        width: 200
        height: 200
        contentWidth: 400
        contentHeight: 400
        clip: true

        ScrollBar.horizontal: ScrollBar {
            visible: false
        }

        ScrollBar.vertical: ScrollBar {
            visible: false
        }

        Rectangle {
            width: 400
            height: 400
            gradient: Gradient {
                GradientStop { position: 0.0; color: "lightsteelblue" }
                GradientStop { position: 1.0; color: "blue" }
            }
        }
    }
}