Remove unused method

framework/core/src/Api/Serializer/GroupSerializer.php

@@ -57,14 +57,6 @@ class GroupSerializer extends AbstractSerializer
         ];
     }
 
-    /**
-     * @return \Tobscure\JsonApi\Relationship
-     */
-    protected function permissions($group)
-    {
-        return $this->hasMany($group, PermissionSerializer::class);
-    }
-
     /**
      * @param string $name
      * @return string