diff --git a/src/openapi/orders/service_engine_orders.yaml b/src/openapi/orders/service_engine_orders.yaml
index 48cc497..c48b7f4 100644
--- a/src/openapi/orders/service_engine_orders.yaml
+++ b/src/openapi/orders/service_engine_orders.yaml
@@ -6878,7 +6878,6 @@ components:
           example: 11
     PostOrder:
       type: object
-      required:
       properties:
         externalOrderId:
           type: string
@@ -6919,7 +6918,8 @@ components:
             Amount of the products to be delivered, in case of saldo quantity is used to define the amount of saldo to be charged in eurocents. If multiple GBO products are added, the same amount of customerTokens will be required.
           example: 1
         createdOn:
-          type: datetime          
+          type: string
+          format: date-time          
           description: |-
             Current datetime, moment client added orderLine to the order
           example: "2024-03-22T09:00:00"
@@ -6929,12 +6929,14 @@ components:
             The orderLineId as known in an external sales system, used for reconcilliation
           example: "MyOrderLine123"
         validFrom:
-          type: datetime
+          type: string
+          format: date-time 
           description: |-
             The moment the chosen product should be activated
           example: "2024-03-30T09:00:00"
         validUntil:
-          type: datetime
+          type: string
+          format: date-time 
           description: |-
             Only required when a product does not have a fixed duration, otherwise it is calculated by the back end system
           example: null
@@ -6946,7 +6948,6 @@ components:
             $ref: "#/components/schemas/PostVoucher"
     PatchOrderLine:
       type: object
-      required:
       properties:
         productId:
           type: integer
@@ -6955,10 +6956,12 @@ components:
           type: integer
           example: 1
         validFrom:
-          type: datetime
+          type: string
+          format: date-time 
           example: "2024-03-30T09:00:00"
         validUntil:
-          type: datetime
+          type: string
+          format: date-time 
           example: null
     PostVoucher:
       type: object