ENGCOM-4110: Fixed redirection issue in Admin-> Content -> Schedule #20967

 - Merge Pull Request #20967 from dominicfernando/magento2:redirect-issue-content-schedule
 - Merged commits:
   1. de694d4
   2. 29daef1

Author: magento-engcom-team

app/code/Magento/Backend/Controller/Adminhtml/System/Design/Save.php

@@ -6,7 +6,12 @@
  */
 namespace Magento\Backend\Controller\Adminhtml\System\Design;
 
-class Save extends \Magento\Backend\Controller\Adminhtml\System\Design
+use Magento\Framework\App\Action\HttpPostActionInterface;
+
+/**
+ * Save design action.
+ */
+class Save extends \Magento\Backend\Controller\Adminhtml\System\Design implements HttpPostActionInterface
 {
     /**
      * Filtering posted data. Converting localized data if needed
@@ -26,6 +31,8 @@ protected function _filterPostData($data)
     }
 
     /**
+     * Save design action.
+     *
      * @return \Magento\Backend\Model\View\Result\Redirect
      */
     public function execute()