[gtk+/gtk-3-22] Add nullable return annotation to gtk_notebook_get_tab_label

[Matthias Clasen <matthiasc src gnome org>]

commit 743eaeecf2a5ff8b3462ba657a97de8a3091db87
Author: Iñaki García Etxebarria <garetxe gmail com>
Date:   Sat Apr 29 13:08:26 2017 +0200

    Add nullable return annotation to gtk_notebook_get_tab_label
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781935

 gtk/gtknotebook.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtknotebook.c b/gtk/gtknotebook.c
index b6b37d1..e75ac50 100644
--- a/gtk/gtknotebook.c
+++ b/gtk/gtknotebook.c
@@ -7310,7 +7310,7 @@ gtk_notebook_popup_disable (GtkNotebook *notebook)
  * %NULL is returned if @child is not in @notebook or
  * if no tab label has specifically been set for @child.
  *
- * Returns: (transfer none): the tab label
+ * Returns: (transfer none) (nullable): the tab label
  */
 GtkWidget *
 gtk_notebook_get_tab_label (GtkNotebook *notebook,