partial fixes in Newsletter module

- PHPDocs
- strict_type

Author: v.sikailo

app/code/Magento/Newsletter/Block/Adminhtml/Problem.php

@@ -83,7 +83,7 @@ protected function _prepareLayout()
     /**
      * Get the html element for unsubscribe button
      *
-     * @return $string
+     * @return string
      */
     public function getUnsubscribeButtonHtml()
     {
@@ -93,7 +93,7 @@ public function getUnsubscribeButtonHtml()
     /**
      * Get the html element for delete button
      *
-     * @return $string
+     * @return string
      */
     public function getDeleteButtonHtml()
     {

app/code/Magento/Newsletter/Controller/Adminhtml/Subscriber/MassDelete.php

@@ -18,10 +18,11 @@ class MassDelete extends Subscriber
      * @var SubscriberFactory
      */
     private $subscriberFactory;
-    
+
     /**
      * @param Context $context
      * @param FileFactory $fileFactory
+     * @param SubscriberFactory|null $subscriberFactory
      */
     public function __construct(
         Context $context,

app/code/Magento/Newsletter/Controller/Manage/Save.php

@@ -3,6 +3,7 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
 
 namespace Magento\Newsletter\Controller\Manage;
 
@@ -65,9 +66,9 @@ public function __construct(
     /**
      * Save newsletter subscription preference action
      *
-     * @return void|null
+     * @return \Magento\Framework\App\ResponseInterface
      */
-    public function execute()
+    public function execute(): \Magento\Framework\App\ResponseInterface
     {
         if (!$this->formKeyValidator->validate($this->getRequest())) {
             return $this->_redirect('customer/account/');
@@ -110,7 +111,7 @@ public function execute()
                 $this->messageManager->addError(__('Something went wrong while saving your subscription.'));
             }
         }
-        $this->_redirect('customer/account/');
+        return $this->_redirect('customer/account/');
     }
 
     /**
@@ -119,7 +120,7 @@ public function execute()
      * @param Customer $customer
      * @return void
      */
-    private function setIgnoreValidationFlag($customer)
+    private function setIgnoreValidationFlag(Customer $customer): void
     {
         $customer->setData('ignore_validation_flag', true);
     }

app/code/Magento/Newsletter/Controller/Subscriber/Confirm.php

@@ -4,15 +4,17 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\Newsletter\Controller\Subscriber;
 
 class Confirm extends \Magento\Newsletter\Controller\Subscriber
 {
     /**
      * Subscription confirm action
-     * @return void
+     * @return \Magento\Framework\Controller\Result\Redirect
      */
-    public function execute()
+    public function execute(): \Magento\Framework\Controller\Result\Redirect
     {
         $id = (int)$this->getRequest()->getParam('id');
         $code = (string)$this->getRequest()->getParam('code');

app/code/Magento/Newsletter/Model/Subscriber.php

@@ -686,7 +686,7 @@ public function confirm($code)
      * Mark receiving subscriber of queue newsletter
      *
      * @param  \Magento\Newsletter\Model\Queue $queue
-     * @return boolean
+     * @return Subscriber
      */
     public function received(\Magento\Newsletter\Model\Queue $queue)
     {