Added comments and strict types enabling

Author: sivaschenko

app/code/Magento/MediaGallery/Model/Directory/Config.php

@@ -3,13 +3,14 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
 
 namespace Magento\MediaGallery\Model\Directory;
 
 use Magento\Framework\Config\DataInterface;
 
 /**
- * Config of Magento Media Gallery Directory.
+ * Media gallery directory config
  */
 class Config
 {

app/code/Magento/MediaGallery/Model/Directory/Config/Converter.php

@@ -3,37 +3,39 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\MediaGallery\Model\Directory\Config;
 
 use Magento\Framework\Config\ConverterInterface;
 
 /**
- * Class Converter
+ * Media gallery directory config converter
  */
 class Converter implements ConverterInterface
 {
     /**
      * Blacklist tag name
      */
-    private CONST BLACKLIST_TAG_NAME = 'blacklist';
+    private const BLACKLIST_TAG_NAME = 'blacklist';
 
     /**
      * Patterns tag name
      */
-    private CONST PATTERNS_TAG_NAME = 'patterns';
+    private const PATTERNS_TAG_NAME = 'patterns';
 
     /**
      * Pattern tag name
      */
-    private CONST PATTERN_TAG_NAME = 'pattern';
+    private const PATTERN_TAG_NAME = 'pattern';
 
     /**
      * Convert dom node to array
      *
      * @param \DOMDocument $source
      * @return array
      */
-    public function convert($source) : array
+    public function convert($source): array
     {
         $result = [];
 

app/code/Magento/MediaGallery/Model/Directory/Config/Reader.php

@@ -3,6 +3,8 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\MediaGallery\Model\Directory\Config;
 
 use Magento\Framework\App\Area;
@@ -12,6 +14,9 @@
 use Magento\Framework\Config\ValidationStateInterface;
 use Magento\Framework\Config\Dom;
 
+/**
+ * Media gallery directory config reader
+ */
 class Reader extends Filesystem implements ReaderInterface
 {
     /**

app/code/Magento/MediaGallery/Model/Directory/Config/SchemaLocator.php

@@ -3,12 +3,17 @@
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
+declare(strict_types=1);
+
 namespace Magento\MediaGallery\Model\Directory\Config;
 
 use Magento\Framework\Module\Dir;
 use Magento\Framework\Module\Dir\Reader;
 use Magento\Framework\Config\SchemaLocatorInterface;
 
+/**
+ * Media gallery directory config schema locator
+ */
 class SchemaLocator implements SchemaLocatorInterface
 {
     /**