[tracker: 1/2] libtracker-sparql: add a few missing GIR annotiations

[Sam Thursfield <sthursfield src gnome org>]

commit e35f5925882e896cd59316db4c7a6da1f6a9af1c
Author: Rasmus Thomsen <oss cogitri dev>
Date:   Tue Jan 26 13:39:29 2021 +0100

    libtracker-sparql: add a few missing GIR annotiations
    
    This makes them consistent with the C docs

 src/libtracker-sparql/tracker-cursor.c            | 2 +-
 src/libtracker-sparql/tracker-namespace-manager.c | 2 +-
 src/libtracker-sparql/tracker-resource.c          | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/src/libtracker-sparql/tracker-cursor.c b/src/libtracker-sparql/tracker-cursor.c
index 78f337cfb..a97767474 100644
--- a/src/libtracker-sparql/tracker-cursor.c
+++ b/src/libtracker-sparql/tracker-cursor.c
@@ -256,7 +256,7 @@ tracker_sparql_cursor_get_n_columns (TrackerSparqlCursor *cursor)
  * Retrieves a string representation of the data in the current
  * row in @column.
  *
- * Returns: a string which must not be freed. %NULL is returned if
+ * Returns: (nullable): a string which must not be freed. %NULL is returned if
  * the column is not in the [0,#n_columns] range.
  */
 const gchar *
diff --git a/src/libtracker-sparql/tracker-namespace-manager.c 
b/src/libtracker-sparql/tracker-namespace-manager.c
index d8f284ca9..e9b2456fd 100644
--- a/src/libtracker-sparql/tracker-namespace-manager.c
+++ b/src/libtracker-sparql/tracker-namespace-manager.c
@@ -183,7 +183,7 @@ tracker_namespace_manager_has_prefix (TrackerNamespaceManager *self,
  * Looks up the namespace URI corresponding to @prefix, or %NULL if the prefix
  * is not known.
  *
- * Returns: a string owned by the #TrackerNamespaceManager, or %NULL
+ * Returns: (nullable): a string owned by the #TrackerNamespaceManager, or %NULL
  */
 const char *
 tracker_namespace_manager_lookup_prefix (TrackerNamespaceManager *self,
diff --git a/src/libtracker-sparql/tracker-resource.c b/src/libtracker-sparql/tracker-resource.c
index 5c64e24c5..500aa870d 100644
--- a/src/libtracker-sparql/tracker-resource.c
+++ b/src/libtracker-sparql/tracker-resource.c
@@ -222,7 +222,7 @@ set_property (GObject      *object,
 
 /**
  * tracker_resource_new:
- * @identifier: A string containing a URI
+ * @identifier: (nullable): A string containing a URI, or %NULL.
  *
  * Creates a TrackerResource instance.
  *