public function transform(FormField $field)
 {
     if (!$field instanceof GridField) {
         throw new Exception(__CLASS__ . ' requires GridField FormField type.');
     }
     $title = $field->Title();
     $list = $field->getList();
     $config = $field->getConfig();
     $result = MultiRecordField::create($field->getName(), $title, $list);
     // Support: GridFieldExtensions (https://github.com/silverstripe-australia/silverstripe-gridfieldextensions)
     $gridFieldAddNewMultiClass = $config->getComponentsByType('GridFieldAddNewMultiClass')->first();
     if ($gridFieldAddNewMultiClass) {
         $classes = $gridFieldAddNewMultiClass->getClasses($field);
         $result->setModelClasses($classes);
     }
     return $result;
 }