Fix wrong ref link in Demo Server Docker Image

src/SCIMConfig.php

@@ -121,7 +121,7 @@ protected function doRead(&$object, $attributes = [])
                                 return route(
                                     'scim.resource',
                                     [
-                                    'resourceType' => 'Group',
+                                    'resourceType' => 'Groups',
                                     'resourceObject' => $object->id ?? "not-saved"
                                     ]
                                 );

tests/BasicTest.php

@@ -557,4 +557,28 @@ public function testPostTopLevelEmptyName()
         $this->assertEquals('[email protected]', $json['urn:ietf:params:scim:schemas:core:2.0:User']['emails'][0]['value']);
         $this->assertEquals('Dr. Marie Jo', $json['urn:ietf:params:scim:schemas:core:2.0:User']['userName']);
     }
+
+    public function testGroupReferencesHaveCorrectUri()
+    {
+        // Get a user with groups to check the $ref URIs
+        $response = $this->get('/scim/v2/Users?startIndex=1&count=1');
+
+        $response->assertStatus(200);
+        $this->assertGreaterThan(0, count($response->json('Resources')));
+
+        $user = $response->json('Resources.0.urn:ietf:params:scim:schemas:core:2.0:User');
+
+        // Check if user has groups
+        if (isset($user['groups']) && count($user['groups']) > 0) {
+            foreach ($user['groups'] as $group) {
+                // Verify that the $ref field contains "Groups" (plural) not "Group" (singular)
+                if (isset($group['$ref'])) {
+                    $this->assertStringContainsString('/scim/v2/Groups/', $group['$ref'], 
+                        'Group reference should use "Groups" (plural) in URI, not "Group" (singular)');
+                    $this->assertStringNotContainsString('/scim/v2/Group/', $group['$ref'],
+                        'Group reference should not use "Group" (singular) in URI');
+                }
+            }
+        }
+    }
 }