[gtk/bilelmoussaoui/g-i] gtk: mark gtk_list_box_get_adjustment as nullable

[Bilal Elmoussaoui <bilelmoussaoui src gnome org>]

commit 1e9bdb4647028c728088b7ff94de15548d7f0335
Author: Bilal Elmoussaoui <bil elmoussaoui gmail com>
Date:   Sat Jan 1 19:05:06 2022 +0100

    gtk: mark gtk_list_box_get_adjustment as nullable
    
    similar to its setter function

 gtk/gtklistbox.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtklistbox.c b/gtk/gtklistbox.c
index 95120f8cef..3a75bc0f3e 100644
--- a/gtk/gtklistbox.c
+++ b/gtk/gtklistbox.c
@@ -1078,7 +1078,7 @@ gtk_list_box_set_adjustment (GtkListBox    *box,
  * Gets the adjustment (if any) that the widget uses to
  * for vertical scrolling.
  *
- * Returns: (transfer none): the adjustment
+ * Returns: (transfer none) (nullable): the adjustment
  */
 GtkAdjustment *
 gtk_list_box_get_adjustment (GtkListBox *box)