+/**
+ * Filter the file of an admin menu sub-menu item.
+ *
+ * @since 4.4.0
+ *
+ * @param string $submenu_file The submenu file.
+ * @param string $parent_file The submenu item's parent file.
+ */
+$submenu_file = apply_filters( 'submenu_file', $submenu_file, $parent_file );
+