protected function fetchAvailableShippingMethods()
    {
        if (!$this->methods) {
            $activeCarriers = $this->getShippingConfig()->getActiveCarriers();
            foreach ($activeCarriers as $carrierCode => $carrierModel) {
                $this->addShippingMethodsFromCarrier($carrierCode, $carrierModel);
            }
        }
        return $this->methods;
    }