diff --git a/Models/AmountGroup.php b/Models/AmountGroup.php
index a93a436..bd8e516 100644
--- a/Models/AmountGroup.php
+++ b/Models/AmountGroup.php
@@ -36,6 +36,11 @@ class AmountGroup
 
     public int $option = 0;
 
+    /**
+     * Constructor.
+     *
+     * @since 1.0.0
+     */
     public function __construct()
     {
         $this->type = new BaseStringL11nType();