XRechnung test suite version release-2026-01-31: UBL document reference interpreted as date

When running Mustang-CLI (`mustang --action validate --source 03.07a-INVOICE_ubl.xml`), way to less rules seem to be applied and there are exceptions not represented in the validation report. ``` [main] INFO com.helger.schematron.api.xslt.AbstractSchematronXSLTBasedResource - Applying Schematron XSLT on XML instance [main] WARN org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter - Failed to parse date ANG987654321 with pattern yyyy-MM-dd java.text.ParseException: Unparseable date: "ANG987654321" at java.base/java.text.DateFormat.parse(DateFormat.java:399) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.parseDate(ZUGFeRDInvoiceImporter.java:1342) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.extractInto(ZUGFeRDInvoiceImporter.java:629) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.setDocument(ZUGFeRDInvoiceImporter.java:340) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.setRawXML(ZUGFeRDInvoiceImporter.java:297) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.setRawXML(ZUGFeRDInvoiceImporter.java:311) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.fromXML(ZUGFeRDInvoiceImporter.java:1462) at org.mustangproject.validator.XMLValidator.checkArithmetics(XMLValidator.java:456) at org.mustangproject.validator.XMLValidator.validate(XMLValidator.java:409) at org.mustangproject.validator.ZUGFeRDValidator.internalValidate(ZUGFeRDValidator.java:199) at org.mustangproject.validator.ZUGFeRDValidator.validate(ZUGFeRDValidator.java:254) at org.mustangproject.commandline.Main.performValidate(Main.java:482) at org.mustangproject.commandline.Main.main(Main.java:442) [main] WARN org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter - Failed to parse date ANG987654321 with pattern yyyy-MM-dd java.text.ParseException: Unparseable date: "ANG987654321" at java.base/java.text.DateFormat.parse(DateFormat.java:399) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.parseDate(ZUGFeRDInvoiceImporter.java:1342) at org.mustangproject.ZUGFeRD.ZUGFeRDInvoiceImporter.extractInto(ZUGFeRDInvoiceImporter.java:629) at org.mustangproject.validator.XMLValidator.checkArithmetics(XMLValidator.java:458) at org.mustangproject.validator.XMLValidator.validate(XMLValidator.java:409) at org.mustangproject.validator.ZUGFeRDValidator.internalValidate(ZUGFeRDValidator.java:199) at org.mustangproject.validator.ZUGFeRDValidator.validate(ZUGFeRDValidator.java:254) at org.mustangproject.commandline.Main.performValidate(Main.java:482) at org.mustangproject.commandline.Main.main(Main.java:442) [main] INFO org.mustangproject.validator.ZUGFeRDValidator - Parsed PDF:absent XML:valid Signature:null Checksum:3BCFED594297D6CDE5D3937CF1C50E93C000B4F2 Profile:urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0 Version:2 Took:2755ms Errors:[] ErrorIDs: [] <?xml version="1.0" encoding="UTF-8"?> <validation filename="03.07a-INVOICE_ubl.xml" datetime="2026-02-23 13:54:53"> <xml> <info> <version>2</version> <profile>urn:cen.eu:en16931:2017#compliant#urn:xeinkauf.de:kosit:xrechnung_3.0</profile> <validator version="2.22.0"/> <rules> <fired>30</fired> <failed>0</failed> </rules> <duration unit="ms">2648</duration> </info> <summary status="valid"/> </xml> <summary status="valid"/> </validation> ``` The specific file is available in https://github.com/itplr-kosit/xrechnung-testsuite/releases/download/v2026-01-31/xrechnung-3.0.2-testsuite-2026-01-31.zip as `instances/standard/03.07a-INVOICE_ubl.xml`. Running the validation against a custom implementation inspired by Mustang-CLI leads to 228 rules being fired, which looks much more correct.