Add return tyoe to `RoomListBoxController::getLink()`

files/lib/system/box/RoomListBoxController.class.php

@@ -6,7 +6,7 @@
  * Use of this software is governed by the Business Source License
  * included in the LICENSE file.
  *
- * Change Date: 2026-09-17
+ * Change Date: 2027-02-02
  *
  * On the date above, in accordance with the Business Source
  * License, use of this software will be governed by version 2
@@ -91,7 +91,7 @@ class RoomListBoxController extends AbstractDatabaseObjectListBoxController
     /**
      * @inheritDoc
      */
-    public function getLink()
+    public function getLink(): string
     {
         return LinkHandler::getInstance()->getControllerLink(RoomListPage::class);
     }