MDL-81328 mod_book: Final deprecation of get_nav_classes

.upgradenotes/MDL-81328-2024101606255550.yml

@@ -0,0 +1,7 @@
+issueNumber: MDL-81328
+notes:
+  mod_book:
+    - message: |-
+        The method book_get_nav_classes has been finally
+        deprecated and will now throw an exception if called.
+      type: deprecated

mod/book/deprecatedlib.php

@@ -38,14 +38,9 @@ function book_get_nav_types() {
 }
 
 /**
- * Returns list of available navigation link CSS classes.
- *
  * @deprecated since Moodle 4.4.
- * @todo MDL-81328 Final deprecation in Moodle 4.8.
- * @return array
  */
+#[\core\attribute\deprecated('book_get_nav_classes', since: '4.4', final: true)]
 function book_get_nav_classes() {
-    debugging(__FUNCTION__ . '() is deprecated. There is no replacement.');
-
-    return ['navtoc', 'navimages', 'navtext'];
+    \core\deprecation::emit_deprecation_if_present(__FUNCTION__);
 }