implemented additional privacy interface

dta/privacy/provider.php

@@ -33,6 +33,7 @@ use \mod_assign\privacy\assign_plugin_request_data;
 class provider implements
         // This plugin does store personal user data.
         \core_privacy\local\metadata\provider,
+        \core_privacy\local\request\data_provider,
         \mod_assign\privacy\assignsubmission_provider,
         \mod_assign\privacy\assignsubmission_user_provider
         {