[gtk/bilelmoussaoui/expressions-annotations: 2/2] gtk: add missing nullable annotations to StringFilter

[Bilal Elmoussaoui <bilelmoussaoui src gnome org>]

commit 3761dbba8b24f4f6ab73163117334b1a5108d88e
Author: Bilal Elmoussaoui <bil elmoussaoui gmail com>
Date:   Mon Mar 22 12:42:19 2021 +0100

    gtk: add missing nullable annotations to StringFilter

 gtk/gtkstringfilter.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkstringfilter.c b/gtk/gtkstringfilter.c
index 21a6b6432b..8e31627990 100644
--- a/gtk/gtkstringfilter.c
+++ b/gtk/gtkstringfilter.c
@@ -396,7 +396,7 @@ gtk_string_filter_set_search (GtkStringFilter *self,
  * Gets the expression that the string filter uses to
  * obtain strings from items.
  *
- * Returns: (transfer none): a `GtkExpression`
+ * Returns: (transfer none) (nullable): a `GtkExpression`
  */
 GtkExpression *
 gtk_string_filter_get_expression (GtkStringFilter *self)
@@ -409,7 +409,7 @@ gtk_string_filter_get_expression (GtkStringFilter *self)
 /**
  * gtk_string_filter_set_expression: (attributes org.gtk.Method.set_property=expression)
  * @self: a `GtkStringFilter`
- * @expression: a `GtkExpression`
+ * @expression: (nullable): a `GtkExpression`
  *
  * Sets the expression that the string filter uses to
  * obtain strings from items.