[libgit2-glib] ggit-ref-spec.c: Fix return annotations

[Igor Gnatenko <ignatenko src gnome org>]

commit 812978e7e04e9d5130e757c9f9262d6a2c19dbdd
Author: Brian C. Lane <bcl redhat com>
Date:   Wed Aug 30 17:33:06 2017 -0700

    ggit-ref-spec.c: Fix return annotations
    
    Add (nullable) as needed.

 libgit2-glib/ggit-ref-spec.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/libgit2-glib/ggit-ref-spec.c b/libgit2-glib/ggit-ref-spec.c
index 65179c4..5d91c96 100644
--- a/libgit2-glib/ggit-ref-spec.c
+++ b/libgit2-glib/ggit-ref-spec.c
@@ -54,7 +54,7 @@ _ggit_ref_spec_wrap (const git_refspec *refspec)
  * Atomically increments the reference count of @refspec by one.
  * This function is MT-safe and may be called from any thread.
  *
- * Returns: a #GgitRefSpec.
+ * Returns: (transfer none) (nullable): a #GgitRefSpec or %NULL.
  **/
 GgitRefSpec *
 ggit_ref_spec_ref (GgitRefSpec *refspec)
@@ -90,7 +90,7 @@ ggit_ref_spec_unref (GgitRefSpec *refspec)
  *
  * Gets the @refspec's source.
  *
- * Returns: the refspec's source.
+ * Returns: (transfer none) (nullable): the refspec's source or %NULL.
  */
 const gchar *
 ggit_ref_spec_get_source (GgitRefSpec *refspec)
@@ -106,7 +106,7 @@ ggit_ref_spec_get_source (GgitRefSpec *refspec)
  *
  * Gets the @refspec's destination.
  *
- * Returns: the refspec's destination.
+ * Returns: (transfer none) (nullable): the refspec's destination or %NULL.
  */
 const gchar *
 ggit_ref_spec_get_destination (GgitRefSpec *refspec)