Revert "Merge branch 'signature-app/wp-576-restorestored-object-version' into 'master'"

This reverts merge request !586

docs/source/_static/code/exports/BirthdateFilter.php

@@ -21,7 +21,7 @@ use Symfony\Component\Validator\Context\ExecutionContextInterface;
 class BirthdateFilter implements ExportElementValidatedInterface, FilterInterface
 {
     // add specific role for this filter
-    public function addRole(): ?string
+    public function addRole()
     {
         // we do not need any new role for this filter, so we return null
         return null;