How to write Vala GLib.DBusProxy async

[fujiwara]

I have a following Vala code:

------------------------- >8 =======================
class Application {
private GLib.DBusProxy m_proxy;
private const string m_notification_watcher =
“<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n” +
“<node name=”/StatusNotifierWatcher">\n" +
" <interface name=“foo.StatusNotifierWatcher”>\n" +
" <property name=“ProtocolVersion” type=“i” access=“read” />\n" +
" \n" +
“\n”;
private const string IFACE = “foo.StatusNotifierWatcher”;

public Application() {
    GLib.DBusConnection connection;
    GLib.DBusNodeInfo node_info;

    try {
        connection = GLib.Bus.get_sync(GLib.BusType.SESSION);
    } catch (GLib.IOError e) {
        warning("Failed to get session bus: " + e.message);
        return;
    }
    try {
        node_info = new GLib.DBusNodeInfo.for_xml(m_notification_watcher);
    } catch (GLib.Error e) {
        warning("Failed to get node info: " + e.message);
        return;
    }
    unowned GLib.DBusInterfaceInfo interface_info =
            node_info.lookup_interface(IFACE);
    GLib.DBusProxy.new.begin(
            connection,
            GLib.DBusProxyFlags.DO_NOT_LOAD_PROPERTIES |
                    GLib.DBusProxyFlags.DO_NOT_CONNECT_SIGNALS,
            interface_info,
            "foo.StatusNotifierWatcher",
            "/StatusNotifierWatcher",
            IFACE,
            null,
            (obj, res) => {
                bus_watcher_ready(obj, res);
    });
}

private void
bus_watcher_ready(GLib.Object? obj, GLib.AsyncResult? res) {
    try {
        m_proxy = GLib.DBusProxy.new.end(res);
    } catch (GLib.IOError e) {
        warning("Failed to call dbus proxy: " + e.message);
    }
}

static void main() {
    new Application();
}

}
------------------------- >8 =======================

When I run valac, I got a deprecated warning of “GLib.DBusProxy.new has been deprecated since vala-0.36. Use DBusProxy”.
But I don’t know how to write GLib.DBusProxy().

I referred https://wiki.gnome.org/Projects/Vala/AsyncSamples and vala/tests but no idea.