ZUGFeRDInvoiceImporter does not properly handle UBL CreditNote documents

[burak-inan]

Summary

The ZUGFeRDInvoiceImporter class fails to correctly parse UBL CreditNote documents because it uses Invoice-specific element names when querying CreditNote XML structures.

Problem

UBL uses different element names for Invoice and CreditNote documents:

Invoice Element	CreditNote Element
InvoiceTypeCode	CreditNoteTypeCode
InvoiceLine	CreditNoteLine
InvoicedQuantity	CreditedQuantity
DueDate	PaymentMeans/PaymentDueDate

Note: According to the Peppol BIS Billing 3.0 CreditNote specification, there is no direct DueDate element for CreditNote. The due date is located at CreditNote/PaymentMeans/PaymentDueDate.

Currently, the extractInto() method only uses Invoice element names, causing CreditNote parsing to fail.

Affected Code Locations

1. ZUGFeRDInvoiceImporter.extractInto() - Type code

Type code extraction only looks for InvoiceTypeCode:

typeCode = this.extractString("/*[local-name()=\"Invoice\" or local-name()=\"CreditNote\"]/*[local-name()=\"InvoiceTypeCode\"]").trim();

2. ZUGFeRDInvoiceImporter.extractInto() - Due date

Due date extraction doesn't account for CreditNote's different structure:

dueDate = this.extractString("/*[local-name()=\"Invoice\" or local-name()=\"CreditNote\"]/*[local-name()=\"DueDate\"]").trim();

3. ZUGFeRDInvoiceImporter.extractInto() - Line items

Line item extraction only looks for InvoiceLine:

xpr = xpath.compile("//*[local-name()=\"IncludedSupplyChainTradeLineItem\"]|//*[local-name()=\"InvoiceLine\"]");

4. Item constructor - Quantity

The Item class constructor uses InvoicedQuantity:

itemMap.getNode(new String[]{"InvoicedQuantity"}).ifPresent((icn) -> {
    this.setQuantity(new BigDecimal(icn.getTextContent().trim()));
    this.product.setUnit(icn.getAttributes().getNamedItem("unitCode").getNodeValue());
});

Suggested Fix

1. Type code extraction

typeCode = this.extractString("/*[local-name()=\"Invoice\"]/*[local-name()=\"InvoiceTypeCode\"] | /*[local-name()=\"CreditNote\"]/*[local-name()=\"CreditNoteTypeCode\"]").trim();

2. Due date extraction

dueDate = this.extractString("/*[local-name()=\"Invoice\" or local-name()=\"CreditNote\"]/*[local-name()=\"DueDate\"] | /*[local-name()=\"CreditNote\"]/*[local-name()=\"PaymentMeans\"]/*[local-name()=\"PaymentDueDate\"]").trim();

3. Line item extraction

xpr = xpath.compile("//*[local-name()=\"IncludedSupplyChainTradeLineItem\"]|//*[local-name()=\"InvoiceLine\"]|//*[local-name()=\"CreditNoteLine\"]");

4. Item constructor quantity extraction

itemMap.getNode(new String[]{"InvoicedQuantity", "CreditedQuantity"}).ifPresent((icn) -> {
    this.setQuantity(new BigDecimal(icn.getTextContent().trim()));
    this.product.setUnit(icn.getAttributes().getNamedItem("unitCode").getNodeValue());
});

5. Removed due date restriction in Zugferd2PullProvider.generateXML() method

Before:

if (trans.getDocumentCode() != null 
    && Arrays.asList(DocumentCodeTypeConstants.CORRECTEDINVOICE, DocumentCodeTypeConstants.CREDITNOTE).contains(trans.getDocumentCode())) {
    hasDueDate = false;
}

After: This restriction has been removed entirely, allowing due dates for corrected invoices and credit notes.

6. Added description null check in Zugferd2PullProvider.buildPaymentTermsXml() method

if(pt.getDescription() != null) {
    paymentTermsXml += "" + pt.getDescription() + "";
}

Environment

• Mustang Version: 2.21.0

[jstaerk]

#1 is what I tried Zugferdinvoiceimporter 383, 605, 608-611 but pls proceed and PR