[libsecret] Secret item schema name is optional

[Daiki Ueno <dueno src gnome org>]

commit 5a217c5cae721afef1273e3d272552e467f7440e
Author: Tomasz Miąsko <tomasz miasko gmail com>
Date:   Fri May 18 00:00:00 2018 +0000

    Secret item schema name is optional
    
    Initialize the schema_name so that NULL is returned when the schema name
    is absent, instead of an uninitialized memory. Mark return value as
    nullable to indicate this for introspection and documentation.

 libsecret/secret-item.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/libsecret/secret-item.c b/libsecret/secret-item.c
index da4740a..ca5e432 100644
--- a/libsecret/secret-item.c
+++ b/libsecret/secret-item.c
@@ -1745,12 +1745,12 @@ secret_item_set_secret_sync (SecretItem *self,
  * Gets the name of the schema that this item was stored with. This is also
  * available at the <literal>xdg:schema</literal> attribute.
  *
- * Returns: (transfer full): the schema name
+ * Returns: (nullable) (transfer full): the schema name
  */
 gchar *
 secret_item_get_schema_name (SecretItem *self)
 {
-       gchar *schema_name;
+       gchar *schema_name = NULL;
        GVariant *variant;
 
        g_return_val_if_fail (SECRET_IS_ITEM (self), NULL);