usergroup: Add fallback route which redirects to contactgroup

application/controllers/UsergroupController.php

@@ -0,0 +1,28 @@
+<?php
+
+/* Icinga DB Web | (c) 2025 Icinga GmbH | GPLv2 */
+
+namespace Icinga\Module\Icingadb\Controllers;
+
+use Icinga\Module\Icingadb\Web\Controller;
+
+/**
+ * @deprecated Will be removed with 1.3, use ContactgroupController instead
+ */
+class UsergroupController extends Controller
+{
+    public function preDispatch()
+    {
+        $url = $this->getRequest()->getUrl();
+        $url->setPath(preg_replace(
+            '~^icingadb/usergroup(?=/|$)~',
+            'icingadb/contactgroup',
+            $url->getPath()
+        ));
+
+        $this->getResponse()
+            ->setHttpResponseCode(301)
+            ->setHeader('Location', $url->getAbsoluteUrl())
+            ->sendResponse();
+    }
+}