ReportForm: Fix reportlet name

Author: Timm Ortloff

library/Reporting/Web/Forms/ReportForm.php

@@ -111,7 +111,7 @@ protected function assemble()
 
             $addElement->getWrapper()->ensureAssembled()->add($removeElement);
 
-            $reportletClass = $group->getPopulatedValue('reportlet');
+            $reportletClass = $group->getPopulatedValue('add_reportlet');
             if (! empty($reportletClass)) {
                 $config = new Form();