[vala/wip/gobject-2.0: 1/8] gobject-2.0: Some cherry-picking from GIR generated binding

[Rico Tzschichholz <ricotz src gnome org>]

commit 6e070a30724efff9644a4bd33d7289e6f41ac02b
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sat Sep 21 10:49:20 2019 +0200

    gobject-2.0: Some cherry-picking from GIR generated binding

 vapi/gobject-2.0.vapi | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/vapi/gobject-2.0.vapi b/vapi/gobject-2.0.vapi
index 77b256455..57eebc535 100644
--- a/vapi/gobject-2.0.vapi
+++ b/vapi/gobject-2.0.vapi
@@ -643,8 +643,8 @@ namespace GLib {
                public unowned GLib.TypeClass? class_peek ();
                public unowned GLib.TypeClass? class_peek_static ();
                public unowned GLib.TypeClass? default_interface_peek ();
-               public GLib.TypeInterface default_interface_ref ();
-               public GLib.TypeClass class_ref ();
+               public unowned GLib.TypeInterface? default_interface_ref ();
+               public unowned GLib.TypeClass? class_ref ();
                public uint depth ();
                [Version (since = "2.34")]
                public void ensure ();