数据未进入观察者admin_user_save_before

Question

我们在admin用户编辑表单中有一个自定义字段，现在当尝试保存此multiselect字段值时，数据不在此字段内

namespace xx\Area\Observer;

use Magento\Framework\Event\ObserverInterface;

class Saveuser implements ObserverInterface
{
    public function execute(\Magento\Framework\Event\Observer $observer)
    {

        $event = $observer->getEvent();
        echo $user = $event->getUser()->getDeliveryAreas();
        die;

    }

}