Fix bug list role assignments returns empty

Author: haphan

src/Identity/v3/Models/Assignment.php

@@ -10,12 +10,15 @@ class Assignment extends OperatorResource implements Listable
     /** @var Role */
     public $role;
 
-    /** @var \stdClass */
+    /** @var array */
     public $scope;
 
     /** @var Group */
     public $group;
 
     /** @var User */
     public $user;
+
+    protected $resourcesKey = 'role_assignments';
+    protected $resourceKey = 'role_assignment';
 }