#20579: Apply suggestions from code review

Co-Authored-By: David Verholen <david@verholen.com>

Author: p-bystritsky

app/code/Magento/SalesRule/Model/Coupon/UpdateCouponUsages.php

@@ -63,7 +63,7 @@ public function __construct(
      * @param bool $increment
      * @return Order
      */
-    public function execute(Order $subject, bool $increment)
+    public function execute(Order $subject, bool $increment): Order
     {
         if (!$subject || !$subject->getAppliedRuleIds()) {
             return $subject;
@@ -115,7 +115,7 @@ private function updateRuleUsages(bool $increment, int $ruleId, int $customerId)
      * @param int $ruleId
      * @param int $customerId
      */
-    private function updateCustomerRuleUsages(bool $increment, int $ruleId, int $customerId)
+    private function updateCustomerRuleUsages(bool $increment, int $ruleId, int $customerId): void
     {
         /** @var \Magento\SalesRule\Model\Rule\Customer $ruleCustomer */
         $ruleCustomer = $this->ruleCustomerFactory->create();
@@ -137,7 +137,7 @@ private function updateCustomerRuleUsages(bool $increment, int $ruleId, int $cus
      * @param bool $increment
      * @param int $customerId
      */
-    private function updateCouponUsages(Order $subject, bool $increment, int $customerId)
+    private function updateCouponUsages(Order $subject, bool $increment, int $customerId): void
     {
         $this->coupon->load($subject->getCouponCode(), 'code');
         if ($this->coupon->getId()) {

app/code/Magento/SalesRule/Model/ResourceModel/Coupon/Usage.php

@@ -30,7 +30,7 @@ protected function _construct()
      * @param bool $increment
      * @return void
      */
-    public function updateCustomerCouponTimesUsed($customerId, $couponId, $increment = true)
+    public function updateCustomerCouponTimesUsed($customerId, $couponId, $increment = true): void
     {
         $connection = $this->getConnection();
         $select = $connection->select();