Merge pull request #14938 from ppenelon/ppenelon-patch-1

FIX Require Discount class on markAsCreditAvailable API method

htdocs/compta/facture/class/api_invoices.class.php

@@ -996,6 +996,8 @@ class Invoices extends DolibarrApi
      */
     public function markAsCreditAvailable($id)
     {
+		require_once DOL_DOCUMENT_ROOT.'/core/class/discount.class.php';
+
         if (!DolibarrApiAccess::$user->rights->facture->creer) {
             throw new RestException(401);
         }