MC-1439: Define API & SPI and mark accordingly

Author: irenelagno

app/code/Magento/PageBuilder/Model/Config.php

@@ -38,7 +38,7 @@ public function __construct(
     /**
      * @return array
      */
-    public function getGroups()
+    public function getGroups() : array
     {
         return $this->get('groups');
     }

app/code/Magento/PageBuilder/Model/ConfigInterface.php

@@ -3,6 +3,8 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\PageBuilder\Model;
 
 /**
@@ -15,15 +17,15 @@ interface ConfigInterface
     /**
      * @return array
      */
-    public function getGroups();
+    public function getGroups() : array;
 
     /**
      * @return array
      */
-    public function getContentTypes();
+    public function getContentTypes() : array;
 
     /**
      * @return bool
      */
-    public function isEnabled();
+    public function isEnabled() : bool;
 }

app/code/Magento/PageBuilder/Setup/DataConverter/Renderer/Map.php

@@ -85,7 +85,7 @@ public function render(array $itemData, array $additionalData = []) : string
      *
      * @param array $eavData
      *
-     *  @return void
+     * @return void
      */
     private function renderMapLocations($eavData) : void
     {