diff --git a/Models/Invoice.php b/Models/Invoice.php
index 5257db4..927cb08 100644
--- a/Models/Invoice.php
+++ b/Models/Invoice.php
@@ -516,6 +516,9 @@ class Invoice implements \JsonSerializable
         $this->elements[] = $element;
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function jsonSerialize() : void
     {
 
diff --git a/Models/InvoiceElement.php b/Models/InvoiceElement.php
index 96fa337..c4e5a6c 100644
--- a/Models/InvoiceElement.php
+++ b/Models/InvoiceElement.php
@@ -273,6 +273,9 @@ class InvoiceElement implements \JsonSerializable
         return $this->totalPriceGross;
     }
 
+    /**
+     * {@inheritdoc}
+     */
     public function jsonSerialize() : void
     {