public function setItems($items)
    {
        $this->_items = $items;
        if (isset($this->_items[0]) && is_array($this->_items[0])) {
            $this->_items = $this->_items[0];
        }
        foreach ($this->_items as $item) {
            $item->owner = $this;
            if (!$item->isValid) {
                $this->isValid = false;
            }
        }
    }