[Bug]: xRechnung/ZUGfeRD export uses Sell-to Customer's Buyer Reference instead of Bill-to Customer's when Bill-to differs

[miljance]

Describe the issue

When the Buyer Reference setting on the E-Document Service is set to "Customer Reference" (E-Invoice Routing No. from the Customer card), and a Sales Invoice has a Bill-to Customer that differs from the Sell-to Customer, the xRechnung / ZUGFeRD XML export writes the Buyer Reference (BT-10) of the Sell-to Customer into cbc:BuyerReference. The correct behavior is to use the Buyer Reference of the Bill-to Customer, since the Bill-to Customer is the actual invoice recipient and the Buyer Reference (Leitweg-ID) is used to route the e-invoice to the correct receiving system.

Expected behavior

When the Buyer Reference is sourced from the Customer card ("Customer Reference" setting) and the Sales Invoice has a Bill-to Customer that differs from the Sell-to Customer, the cbc:BuyerReference (BT-10) in the exported XML should contain the E-Invoice Routing No. of the Bill-to Customer, not the Sell-to Customer.

Steps to reproduce

1. Use Business Central for Germany.
2. Enable E-Document Service for XRechnung.
3. In setup:
   • Set Buyer Reference Mandatory = Yes
   • Set Buyer Reference = Customer Reference
4. Configure a Workflow and a Document Sending Profile for XRechnung (per [docs]). Mark the sending profile as default.
5. Create two Customers:
   • Customer A with E-Invoice Routing No. = 11-AAA-11
   • Customer B with E-Invoice Routing No. = 22-BBB-22
6. Create a new Sales Invoice:
   • Sell-to Customer = Customer A
   • Bill-to Customer = Customer B
7. Add a Sales Line with any value.
8. Post the Sales Invoice.
9. Open the Posted Sales Invoice → Related → E-Document → Open E-Document.
10. From E-Document Logs, export the XML file.
11. Inspect <cbc:BuyerReference> in the XML.
    • Actual result: <cbc:BuyerReference>11-AAA-11</cbc:BuyerReference> (Sell-to Customer's E-Invoice Routing No.)
    • Expected result: <cbc:BuyerReference>22-BBB-22</cbc:BuyerReference> (Bill-to Customer's E-Invoice Routing No.)

Additional context

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