Added thumb to Audio entity.

Author: noplanman

src/Entities/Audio.php

@@ -15,14 +15,23 @@
  *
  * @link https://core.telegram.org/bots/api#audio
  *
- * @method string getFileId()    Unique identifier for this file
- * @method int    getDuration()  Duration of the audio in seconds as defined by sender
- * @method string getPerformer() Optional. Performer of the audio as defined by sender or by audio tags
- * @method string getTitle()     Optional. Title of the audio as defined by sender or by audio tags
- * @method string getMimeType()  Optional. MIME type of the file as defined by sender
- * @method int    getFileSize()  Optional. File size
+ * @method string    getFileId()    Unique identifier for this file
+ * @method int       getDuration()  Duration of the audio in seconds as defined by sender
+ * @method string    getPerformer() Optional. Performer of the audio as defined by sender or by audio tags
+ * @method string    getTitle()     Optional. Title of the audio as defined by sender or by audio tags
+ * @method string    getMimeType()  Optional. MIME type of the file as defined by sender
+ * @method int       getFileSize()  Optional. File size
+ * @method PhotoSize getThumb()     Optional. Thumbnail of the album cover to which the music file belongs
  */
 class Audio extends Entity
 {
-
+    /**
+     * {@inheritdoc}
+     */
+    protected function subEntities()
+    {
+        return [
+            'thumb' => PhotoSize::class,
+        ];
+    }
 }