protected function isValidFieldname(FieldStorageConfig $field_storage, FieldableEntityInterface $entity)
 {
     $comment_field_name_ok = FALSE;
     if ($field_storage->getTargetEntityTypeId() !== 'comment') {
         return TRUE;
     }
     $field_name = $field_storage->get('field_name');
     // Check if the 'comment' field name exists on the 'commented' entity type.
     // @todo: Still not waterproof. You could have a field on a non-relevant entity_type.
     foreach (_workflow_info_fields() as $key => $info) {
         if ($info->getName() == $field_name && $info->getTargetEntityTypeId() !== 'comment') {
             $comment_field_name_ok = TRUE;
         }
     }
     return $comment_field_name_ok;
 }