Requires the Edit permission for invoices.

Changing invoice_number, supplier, or outlet triggers a duplicate check against existing invoices in the same outlet. If a conflict is found, the endpoint returns a 409 Conflict with an INVOICE_NUMBER_DUPLICATED_EXCEPTION error.

A purchase_orders list that leaves out a purchase order already linked to the invoice is refused with 409 while the invoice has a credit request that was not withdrawn. The response lists those credit requests in credit_request_ids, and nothing in the request is saved. Adding purchase orders is not affected.