[vte] widget: Add missing (nullable) annotations

[Christian Persch <chpe src gnome org>]

commit def6a1c39389e12e0b7d24e024b8d1b3931f7975
Author: Christian Persch <chpe src gnome org>
Date:   Thu Nov 21 20:01:30 2019 +0100

    widget: Add missing (nullable) annotations
    
    Fixes https://gitlab.gnome.org/GNOME/vte/issues/190

 src/vtegtk.cc | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)
---
diff --git a/src/vtegtk.cc b/src/vtegtk.cc
index ce2a7966..a20a0e75 100644
--- a/src/vtegtk.cc
+++ b/src/vtegtk.cc
@@ -2180,7 +2180,7 @@ vte_terminal_match_add_regex(VteTerminal *terminal,
  * vte_terminal_match_add(), then expressions are checked in the order in
  * which they were added.
  *
- * Returns: (transfer full): a newly allocated string which matches one of the previously
+ * Returns: (transfer full) (nullable): a newly allocated string which matches one of the previously
  *   set regular expressions
  *
  * Deprecated: 0.46: Use vte_terminal_match_check_event() instead.
@@ -2211,8 +2211,8 @@ vte_terminal_match_check(VteTerminal *terminal,
  * vte_terminal_match_add(), then expressions are checked in the order in
  * which they were added.
  *
- * Returns: (transfer full): a newly allocated string which matches one of the previously
- *   set regular expressions
+ * Returns: (transfer full) (nullable): a newly allocated string which matches one of the previously
+ *   set regular expressions, or %NULL if there is no match
  */
 char *
 vte_terminal_match_check_event(VteTerminal *terminal,
@@ -2235,7 +2235,8 @@ vte_terminal_match_check_event(VteTerminal *terminal,
  * like "http://";, "https://";, "file://", "mailto:"; etc. This is, however, not enforced by VTE.
  * The caller must tolerate the returned string potentially not being a valid URI.
  *
- * Returns: (transfer full): a newly allocated string containing the target of the hyperlink
+ * Returns: (transfer full) (nullable): a newly allocated string containing the target of the hyperlink,
+ *  or %NULL
  *
  * Since: 0.50
  */