public function execute(\Magento\Framework\Event\Observer $observer)
    {
        /** @var \Magento\Quote\Api\Data\CartInterface $quote */
        $quote = $observer->getQuote();

        /** @var \Magento\Quote\Api\Data\AddressInterface $shippingAddress */
        $shippingAddress = $quote->getShippingAddress();
        if ($shippingAddress) {
            $shippingMethod = $shippingAddress->getShippingMethod();
            if ($shippingMethod) {
                $methodCode = \Smile\StoreDelivery\Model\Carrier::METHOD_CODE;
                $carrier    = $this->carrierFactory->getIfActive($methodCode);
                if ($carrier && $shippingMethod === sprintf('%s_%s', $methodCode, $carrier->getCarrierCode())) {
                    $billingAddress = $quote->getBillingAddress();

                    if (!$shippingAddress->getFirstname()) {
                        $shippingAddress->setFirstname($billingAddress->getFirstname());
                    }
                    if (!$shippingAddress->getLastname()) {
                        $shippingAddress->setLastname($billingAddress->getLastname());
                    }
                    if (!$shippingAddress->getTelephone()) {
                        $shippingAddress->setTelephone($billingAddress->getTelephone());
                    }
                }
            }
        }
    }