I am trying to update the order detail lines, specifically setting the "PickingSlipPrinted" flag to true, what would be the minimum data I need to send to the service?

I've tried the below, but, it just keeps returning that certain fields cannot be empty which seems to carry on until I will eventually have to fill in ALL the fields?

{
"OrderUniquifier": 12345,
"OrderPrintStatus": "3",
"OrderDetails": [
{
"OrderUniquifier": 1234,
"LineNumber": 1,
"PickingSlipPrinted": true,
}
],
"UpdateOperation": "Update"
}