This adds support for multiple invoice referenced documents (BG-3)

library/src/main/java/org/mustangproject/Invoice.java

@@ -38,7 +38,7 @@
 @JsonInclude(JsonInclude.Include.NON_EMPTY)
 public class Invoice implements IExportableTransaction {
 
-	protected String documentName = null, documentCode = null, number = null, ownOrganisationFullPlaintextInfo = null, referenceNumber = null, shipToOrganisationID = null, shipToOrganisationName = null, shipToStreet = null, shipToZIP = null, shipToLocation = null, shipToCountry = null, buyerOrderReferencedDocumentID = null, invoiceReferencedDocumentID = null, buyerOrderReferencedDocumentIssueDateTime = null, ownForeignOrganisationID = null, ownOrganisationName = null, currency = null, paymentTermDescription = null;
+	protected String documentName = null, documentCode = null, number = null, ownOrganisationFullPlaintextInfo = null, referenceNumber = null, shipToOrganisationID = null, shipToOrganisationName = null, shipToStreet = null, shipToZIP = null, shipToLocation = null, shipToCountry = null, buyerOrderReferencedDocumentID = null, buyerOrderReferencedDocumentIssueDateTime = null, ownForeignOrganisationID = null, ownOrganisationName = null, currency = null, paymentTermDescription = null;
 	protected Date issueDate = null, dueDate = null, deliveryDate = null;
 	protected TradeParty sender = null, recipient = null, deliveryAddress = null, payee = null;
 	protected ArrayList<CashDiscount> cashDiscounts = null;
@@ -57,7 +57,12 @@ public class Invoice implements IExportableTransaction {
 	protected ArrayList<IZUGFeRDAllowanceCharge> Allowances = new ArrayList<>(),
 		Charges = new ArrayList<>(), LogisticsServiceCharges = new ArrayList<>();
 	protected IZUGFeRDPaymentTerms paymentTerms = null;
+
+	protected String invoiceReferencedDocumentID = null;
 	protected Date invoiceReferencedIssueDate;
+	// New field for storing Invoiced Object Identifier (BG-3)
+	protected ArrayList<ReferencedDocument> invoiceReferencedDocuments = null;
+
 	protected String specifiedProcuringProjectID = null;
 	protected String specifiedProcuringProjectName = null;
 	protected String despatchAdviceReferencedDocumentID = null;
@@ -148,6 +153,7 @@ public Invoice setNumber(String number) {
 	 */
 	public Invoice setCorrection(String number) {
 		setInvoiceReferencedDocumentID(number);
+		addInvoiceReferencedDocument(new ReferencedDocument(number));
 		documentCode = DocumentCodeTypeConstants.CORRECTEDINVOICE;
 		return this;
 	}
@@ -546,6 +552,26 @@ public Invoice setSender(TradeParty sender) {
 		return this;
 	}
 
+	// Getter for BG-3
+	@Override
+	public ArrayList<ReferencedDocument> getInvoiceReferencedDocuments() {
+		return invoiceReferencedDocuments;
+	}
+
+	// Setter for BG-3
+	public void setInvoiceReferencedDocuments(ArrayList<ReferencedDocument> invoiceReferencedDocuments) {
+		this.invoiceReferencedDocuments = invoiceReferencedDocuments;
+	}
+
+	// Method to add a single ReferencedDocument for BG-3
+	public Invoice addInvoiceReferencedDocument(ReferencedDocument doc) {
+		if (invoiceReferencedDocuments == null) {
+			invoiceReferencedDocuments = new ArrayList<>();
+		}
+		invoiceReferencedDocuments.add(doc);
+		return this;
+	}
+
 	@Override
 	public IZUGFeRDAllowanceCharge[] getZFAllowances() {
 		if (Allowances.isEmpty()) {

library/src/main/java/org/mustangproject/ReferencedDocument.java

@@ -2,6 +2,8 @@
 
 import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 import com.fasterxml.jackson.annotation.JsonInclude;
+import java.util.Date;
+
 import org.mustangproject.ZUGFeRD.IReferencedDocument;
 import org.mustangproject.util.NodeMap;
 import org.w3c.dom.Node;
@@ -13,20 +15,33 @@ public class ReferencedDocument implements IReferencedDocument {
 	String issuerAssignedID;
 	String typeCode;
 	String referenceTypeCode;
+	Date formattedIssueDateTime;
 
 	public ReferencedDocument(String issuerAssignedID, String typeCode, String referenceTypeCode) {
-		this.issuerAssignedID = issuerAssignedID;
+		this(issuerAssignedID);
 		this.typeCode = typeCode;
 		this.referenceTypeCode = referenceTypeCode;
 	}
 
+	public ReferencedDocument(String issuerAssignedID, String typeCode, String referenceTypeCode, Date formattedIssueDateTime) {
+		this(issuerAssignedID, typeCode, referenceTypeCode);
+		this.formattedIssueDateTime = formattedIssueDateTime;
+	}
+
 	public ReferencedDocument(String issuerAssignedID, String referenceTypeCode) {
+		this(issuerAssignedID, "916", referenceTypeCode); // additional invoice related document
+	}
+
+	public ReferencedDocument(String issuerAssingedID, Date formattedIssueDateTime) {
+		this(issuerAssingedID);
+		this.formattedIssueDateTime = formattedIssueDateTime;
+	}
+
+	public ReferencedDocument(String issuerAssignedID) {
 		this.issuerAssignedID = issuerAssignedID;
-		this.typeCode = "916"; // additional invoice related document
-		this.referenceTypeCode = referenceTypeCode;
 	}
 
-    /***
+	/***
 	 * sets an ID assigned by the sender
 	 * @param issuerAssignedID the ID as a string :-)
 	 */
@@ -50,6 +65,15 @@ public void setReferenceTypeCode(String referenceTypeCode) {
 		this.referenceTypeCode = referenceTypeCode;
 	}
 
+	/**
+	 * issue date of this line
+	 *
+	 * @param formattedIssueDateTime as Date
+	 */
+	public void setFormattedIssueDateTime(Date formattedIssueDateTime) {
+		this.formattedIssueDateTime = formattedIssueDateTime;
+	}
+
 	@Override
 	public String getIssuerAssignedID() {
 		return issuerAssignedID;
@@ -65,13 +89,20 @@ public String getReferenceTypeCode() {
 		return referenceTypeCode;
 	}
 
+	@Override
+	public Date getFormattedIssueDateTime()
+	{
+		return formattedIssueDateTime;
+	}
+
 	public static ReferencedDocument fromNode(Node node) {
 		if (!node.hasChildNodes()) {
 			return null;
 		}
 		NodeMap nodes = new NodeMap(node);
 		return new ReferencedDocument(nodes.getAsStringOrNull("IssuerAssignedID", "ID"),
 			nodes.getAsStringOrNull("TypeCode", "DocumentTypeCode"),
-			nodes.getAsStringOrNull("ReferenceTypeCode"));
+			nodes.getAsStringOrNull("ReferenceTypeCode"),
+			XMLTools.tryDate(nodes.getAsStringOrNull("FormattedIssueDateTime")));
 	}
 }

library/src/main/java/org/mustangproject/ZUGFeRD/IExportableTransaction.java

@@ -30,11 +30,13 @@
  * */
 
 import java.math.BigDecimal;
-import java.util.Date;
+import java.util.ArrayList;
+import java.util.Date; 
 import java.util.List;
 
 import org.mustangproject.FileAttachment;
 import org.mustangproject.IncludedNote;
+import org.mustangproject.ReferencedDocument;
 import org.mustangproject.ZUGFeRD.model.DocumentCodeTypeConstants;
 
 /***
@@ -424,13 +426,23 @@ default String getBuyerOrderReferencedDocumentID() {
 	 *
 	 * @return the ID of the document
 	 */
+	@Deprecated
 	default String getInvoiceReferencedDocumentID() {
 		return null;
 	}
 
+	@Deprecated
 	default Date getInvoiceReferencedIssueDate() {
 		return null;
 	}
+
+	/**
+	 * Getter for BG-3
+	 * @return list of documents
+	 */
+	default ArrayList<ReferencedDocument> getInvoiceReferencedDocuments() {
+		return null;
+	}
 
 	/**
 	 * get the issue timestamp of the BuyerOrderReferencedDocument, which sits in

library/src/main/java/org/mustangproject/ZUGFeRD/IReferencedDocument.java

@@ -1,5 +1,7 @@
 package org.mustangproject.ZUGFeRD;
 
+import java.util.Date;
+
 public interface IReferencedDocument {
 
 	/***
@@ -20,4 +22,12 @@ public interface IReferencedDocument {
 	 */
 	String getReferenceTypeCode();
 
+	/***
+	 * 
+	 * issue date of this line
+	 *
+	 * @return date of the issue
+	 */
+	Date getFormattedIssueDateTime();
+
 }

library/src/main/java/org/mustangproject/ZUGFeRD/OXPullProvider.java

@@ -459,6 +459,19 @@ public void generateXML(IExportableTransaction trans) {
 			}
 			xml += "</ram:InvoiceReferencedDocument>";
 		}
+		if (trans.getInvoiceReferencedDocuments() != null) {
+			for (var doc : trans.getInvoiceReferencedDocuments()) {
+				xml += "<ram:InvoiceReferencedDocument>"
+						+ "<ram:IssuerAssignedID>"
+						+ XMLTools.encodeXML(doc.getIssuerAssignedID()) + "</ram:IssuerAssignedID>";
+				if (doc.getFormattedIssueDateTime() != null) {
+					xml += "<ram:FormattedIssueDateTime>"
+							+ DATE.qdtFormat(doc.getFormattedIssueDateTime())
+							+ "</ram:FormattedIssueDateTime>";
+				}
+				xml += "</ram:InvoiceReferencedDocument>";
+			}
+		}
 
 		xml += "</ram:ApplicableHeaderTradeSettlement>";
 		// + " <IncludedSupplyChainTradeLineItem>"

library/src/main/java/org/mustangproject/ZUGFeRD/ZUGFeRD2PullProvider.java

@@ -893,6 +893,19 @@ public void generateXML(IExportableTransaction trans) {
 			}
 			xml += "</ram:InvoiceReferencedDocument>";
 		}
+		if (trans.getInvoiceReferencedDocuments() != null) {
+			for (var doc : trans.getInvoiceReferencedDocuments()) {
+				xml += "<ram:InvoiceReferencedDocument>"
+						+ "<ram:IssuerAssignedID>"
+						+ XMLTools.encodeXML(doc.getIssuerAssignedID()) + "</ram:IssuerAssignedID>";
+				if (doc.getFormattedIssueDateTime() != null) {
+					xml += "<ram:FormattedIssueDateTime>"
+							+ DATE.qdtFormat(doc.getFormattedIssueDateTime())
+							+ "</ram:FormattedIssueDateTime>";
+				}
+				xml += "</ram:InvoiceReferencedDocument>";
+			}
+		}
 
 		xml += "</ram:ApplicableHeaderTradeSettlement>";
 		// + "<IncludedSupplyChainTradeLineItem>\n"

library/src/main/java/org/mustangproject/ZUGFeRD/ZUGFeRDInvoiceImporter.java

@@ -816,6 +816,23 @@ public Invoice extractInto(Invoice zpp) throws XPathExpressionException, ParseEx
 		}
 		zpp.setInvoiceReferencedDocumentID(extractString("//*[local-name()=\"InvoiceReferencedDocument\"]/*[local-name()=\"IssuerAssignedID\"]|//*[local-name()=\"BillingReference\"]/*[local-name()=\"InvoiceDocumentReference\"]/*[local-name()=\"ID\"]"));
 
+		xpr = xpath.compile("//*[local-name()=\"InvoiceReferencedDocument\"]");
+		NodeList nodes = (NodeList) xpr.evaluate(getDocument(), XPathConstants.NODESET);
+
+		if (nodes.getLength() != 0) {
+			for (int i = 0; i < nodes.getLength(); i++) {
+
+				Node currentItemNode = nodes.item(i);
+				ReferencedDocument doc = ReferencedDocument.fromNode(currentItemNode);
+				if (doc != null 
+						&& (!Objects.equals(zpp.getInvoiceReferencedDocumentID(), doc.getIssuerAssignedID()) 
+						|| !Objects.equals(zpp.getInvoiceReferencedIssueDate(), doc.getFormattedIssueDateTime())))
+				{
+					zpp.addInvoiceReferencedDocument(doc);
+				}
+			}
+		}
+
 		zpp.setOwnOrganisationName(extractString("//*[local-name()=\"SellerTradeParty\"]/*[local-name()=\"Name\"]|//*[local-name()=\"AccountingSupplierParty\"]/*[local-name()=\"Party\"]/*[local-name()=\"PartyName\"]").trim());
 
 		String rounding = extractString("//*[local-name()=\"SpecifiedTradeSettlementHeaderMonetarySummation\"]/*[local-name()=\"RoundingAmount\"]|//*[local-name()=\"LegalMonetaryTotal\"]/*[local-name()=\"Party\"]/*[local-name()=\"PayableRoundingAmount\"]");
@@ -834,7 +851,7 @@ public Invoice extractInto(Invoice zpp) throws XPathExpressionException, ParseEx
 		}
 
 		xpr = xpath.compile("//*[local-name()=\"IncludedSupplyChainTradeLineItem\"]|//*[local-name()=\"InvoiceLine\"]");
-		NodeList nodes = (NodeList) xpr.evaluate(getDocument(), XPathConstants.NODESET);
+		nodes = (NodeList) xpr.evaluate(getDocument(), XPathConstants.NODESET);
 
 		if (nodes.getLength() != 0) {
 			for (int i = 0; i < nodes.getLength(); i++) {

library/src/test/java/org/mustangproject/ZUGFeRD/ZF2PushTest.java

@@ -542,7 +542,7 @@ public void testPushEdge() {
 					.addAllowance(new Allowance(new BigDecimal(0.2)).setReason("discount").setTaxPercent(new BigDecimal(16)))
 					.addCashDiscount(new CashDiscount(new BigDecimal(2), 14))
 					.setDeliveryDate(sdf.parse("2020-11-02")).setNumber(number).setVATDueDateTypeCode(EventTimeCodeTypeConstants.PAYMENT_DATE)
-					.setInvoiceReferencedDocumentID("abc123")
+					.setInvoiceReferencedDocumentID("abc123").addInvoiceReferencedDocument(new ReferencedDocument("abcd1234"))
 				);
 			} catch (ParseException e) {
 				e.printStackTrace();
@@ -587,6 +587,8 @@ public void testPushEdge() {
 			Invoice i = zii.extractInvoice();
 
 			assertEquals("abc123", i.getInvoiceReferencedDocumentID());
+			assertEquals(1, i.getInvoiceReferencedDocuments().size());
+			assertEquals("abcd1234", i.getInvoiceReferencedDocuments().get(0).getIssuerAssignedID());
 			assertEquals("4304171000002", i.getRecipient().getGlobalID());
 			assertEquals("2001015001325", i.getZFItems()[0].getProduct().getGlobalID());
 			assertEquals(orgID, i.getSender().getID());