The adjustment setters takes a nullable and so should the getters be annotated
*
* Retrieves the `GtkAdjustment` used for horizontal scrolling.
*
- * Returns: (transfer none): horizontal `GtkAdjustment`.
+ * Returns: (transfer none) (nullable): horizontal `GtkAdjustment`.
*/
GtkAdjustment *
gtk_scrollable_get_hadjustment (GtkScrollable *scrollable)
*
* Retrieves the `GtkAdjustment` used for vertical scrolling.
*
- * Returns: (transfer none): vertical `GtkAdjustment`.
+ * Returns: (transfer none) (nullable): vertical `GtkAdjustment`.
*/
GtkAdjustment *
gtk_scrollable_get_vadjustment (GtkScrollable *scrollable)