Work Order Update using API gives error

Hello,

I am trying to update a work order using Work Order update API: REST API for Oracle Supply Chain Management Cloud - Update one work order

However, I keep getting this error: CompletedQuantity: Attribute CompletedQuantity in view object WorkOrder cannot be set.

I would request you all to please help me understand how to resolve this error. Thanks in advance for your inputs.

Request payload is as follows:

{

  "ItemNumber": "KBX1030.Terminal Box",

  "WorkOrderSerialNumber": 

  [

  "AT_1030_0334",

  "AT_1030_0333"

  ],

  "CompletedQuantity" :2,

  "WorkOrderNumber": "CKH-WO-1082",

   "PlannedStartQuantity": 2,

  "CompletionSubinventoryCode": "H3G_FGI"

}