magento/magento2#23143: Code optimization for the offline shipping methods

app/code/Magento/OfflineShipping/Model/Carrier/Flatrate.php

@@ -69,6 +69,8 @@ public function __construct(
     }
 
     /**
+     * Collect and get rates
+     *
      * @param RateRequest $request
      * @return Result|bool
      * @SuppressWarnings(PHPMD.CyclomaticComplexity)
@@ -97,6 +99,8 @@ public function collectRates(RateRequest $request)
     }
 
     /**
+     * Get count of free boxes
+     *
      * @param RateRequest $request
      * @return int
      */
@@ -120,14 +124,18 @@ private function getFreeBoxesCount(RateRequest $request)
     }
 
     /**
+     * Get allowed shipping methods
+     *
      * @return array
      */
     public function getAllowedMethods()
     {
-        return ['flatrate' => $this->getConfigData('name')];
+        return [$this->_code => $this->getConfigData('name')];
     }
 
     /**
+     * Returns shipping price
+     *
      * @param RateRequest $request
      * @param int $freeBoxes
      * @return bool|float
@@ -154,6 +162,8 @@ private function getShippingPrice(RateRequest $request, $freeBoxes)
     }
 
     /**
+     * Creates result method
+     *
      * @param int|float $shippingPrice
      * @return \Magento\Quote\Model\Quote\Address\RateResult\Method
      */
@@ -174,6 +184,8 @@ private function createResultMethod($shippingPrice)
     }
 
     /**
+     * Returns free boxes count of children
+     *
      * @param mixed $item
      * @return mixed
      */

app/code/Magento/OfflineShipping/Model/Carrier/Freeshipping.php

@@ -144,6 +144,6 @@ protected function _updateFreeMethodQuote($request)
      */
     public function getAllowedMethods()
     {
-        return ['freeshipping' => $this->getConfigData('name')];
+        return [$this->_code => $this->getConfigData('name')];
     }
 }

app/code/Magento/OfflineShipping/Model/Carrier/Pickup.php

@@ -58,6 +58,8 @@ public function __construct(
     }
 
     /**
+     * Collect and get rates
+     *
      * @param RateRequest $request
      * @return \Magento\Shipping\Model\Rate\Result
      * @SuppressWarnings(PHPMD.UnusedFormalParameter)
@@ -75,6 +77,6 @@ public function collectRates(RateRequest $request)
      */
     public function getAllowedMethods()
     {
-        return ['pickup' => __('Store Pickup')];
+        return [$this->_code => __('Store Pickup')];
     }
 }