add DeliveryNoteReferencedDocument per Item Line ID

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

@@ -48,6 +48,7 @@ public class Item implements IZUGFeRDExportableItem {
  	protected TradeParty lineSeller;
 	protected String deliveryNoteReferencedDocumentID = null;
 	protected Date deliveryNoteReferencedDocumentDate = null;
+	protected String deliveryNoteReferencedDocumentLineID = null;
 	//protected HashMap<String, String> attributes = new HashMap<>();
 
 	/***
@@ -194,6 +195,9 @@ public class Item implements IZUGFeRDExportableItem {
 				dn.getAsString("IssuerAssignedID")
 					.ifPresent(this::setDeliveryNoteReferencedDocumentID);
 
+				dn.getAsString("LineID")
+						.ifPresent(this::setDeliveryNoteReferencedDocumentLineID);
+
 				dn.getAsNodeMap("FormattedIssueDateTime")
 					.flatMap(fdt -> fdt.getNode("DateTimeString"))
 					.map(XMLTools::getNodeValue)
@@ -734,4 +738,15 @@ public class Item implements IZUGFeRDExportableItem {
 		return this;
 	}
 
+	@Override
+	public String getDeliveryNoteReferencedDocumentLineID() {
+		return deliveryNoteReferencedDocumentLineID;
+	}
+
+
+	public Item setDeliveryNoteReferencedDocumentLineID(String deliveryNoteReferencedDocumentLineID) {
+		this.deliveryNoteReferencedDocumentLineID = deliveryNoteReferencedDocumentLineID;
+		return this;
+	}
+
 }

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

@@ -267,4 +267,14 @@ public interface IZUGFeRDExportableItem extends IAbsoluteValueProvider{
 		return null;
 	}
 
+	/**
+	 * get delivery note document LineID (per Item - ZUGFeRD EXTENDED)
+	 * rsm:SupplyChainTradeTransaction/ram:IncludedSupplyChainTradeLineItem/ram:SpecifiedLineTradeDelivery/ram:DeliveryNoteReferencedDocument/LineID
+	 *
+	 * @return the LineID of the delivery note document item
+	 */
+	default String getDeliveryNoteReferencedDocumentLineID() {
+		return null;
+	}
+
 }

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

@@ -539,6 +539,7 @@ public class ZUGFeRD2PullProvider implements IXMLProvider {
 					if (currentItem.getDeliveryNoteReferencedDocumentID() != null && !currentItem.getDeliveryNoteReferencedDocumentID().trim().isEmpty()) {
 						xml += "<ram:DeliveryNoteReferencedDocument>";
 						xml += "<ram:IssuerAssignedID>" + XMLTools.encodeXML(currentItem.getDeliveryNoteReferencedDocumentID()) + "</ram:IssuerAssignedID>";
+						xml += "<ram:LineID>" + XMLTools.encodeXML(currentItem.getDeliveryNoteReferencedDocumentLineID()) + "</ram:LineID>";
 						if (currentItem.getDeliveryNoteReferencedDocumentDate() != null) {
 							final SimpleDateFormat dateFormat102 = new SimpleDateFormat("yyyyMMdd");
 							xml += "<ram:FormattedIssueDateTime><qdt:DateTimeString format=\"102\">"+XMLTools.encodeXML(dateFormat102.format(currentItem.getDeliveryNoteReferencedDocumentDate()))+"</qdt:DateTimeString></ram:FormattedIssueDateTime>";

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

@@ -746,6 +746,10 @@ public class ZUGFeRDImporter extends ZUGFeRDInvoiceImporter {
 								if (subnode != null) {
 									lineItem.setDeliveryNoteReferencedDocumentID(XMLTools.getNodeValue(subnode));
 								}
+								subnode = getNodeByName(node.getChildNodes(), "LineID");
+								if (subnode != null) {
+									lineItem.setDeliveryNoteReferencedDocumentLineID(XMLTools.getNodeValue(subnode));
+								}
 								node = getNodeByName(node.getChildNodes(), "FormattedIssueDateTime");
 								if (node != null) {
 									NodeList FormattedIssueDateTimeChilds = node.getChildNodes();

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

@@ -104,6 +104,7 @@ public class MustangReaderWriterCustomXMLTest extends TestCase {
 					"<ram:BilledQuantity unitCode=\"HUR\">1.0000</ram:BilledQuantity>\n" +
 					"<ram:DeliveryNoteReferencedDocument>\n" +
 					"<ram:IssuerAssignedID>deliverynote123</ram:IssuerAssignedID>\n" +
+				    "<ram:LineID>deliverypos456</ram:LineID>\n" +
 					"<ram:FormattedIssueDateTime>\n" +
 					"<udt:DateTimeString format=\"102\">20260114</udt:DateTimeString>\n" +
 					"</ram:FormattedIssueDateTime>\n" +
@@ -288,6 +289,7 @@ public class MustangReaderWriterCustomXMLTest extends TestCase {
 		assertEquals(zi.getHolder(), "Bei Spiel GmbH");
 		assertEquals(zi.getForeignReference(), "RE-20171118/506");
 		assertEquals(zi.getLineItemList().get(0).getDeliveryNoteReferencedDocumentID(), "deliverynote123");
+		assertEquals(zi.getLineItemList().get(0).getDeliveryNoteReferencedDocumentLineID(), "deliverypos456");
 		try {
 			assertEquals(zi.getLineItemList().get(0).getDeliveryNoteReferencedDocumentDate(), new SimpleDateFormat("dd.MM.yyyy").parse("14.01.2026"));
 		} catch (ParseException e) {

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

@@ -614,6 +614,7 @@ public class ZF2PushTest extends TestCase {
 						addAdditionalReference(dr2).addBuyerOrderReferencedDocumentID("orderId").addBuyerOrderReferencedDocumentLineID("xxx").addReferencedLineID("xxx")
 						.addNote("item level 1/1").addAllowance(new Allowance(new BigDecimal(0.02)).setReason("item discount").setTaxPercent(new BigDecimal(16))).setDetailedDeliveryPeriod(sdf.parse("2020-01-13"), sdf.parse("2020-01-15"))
 						.setDeliveryNoteReferencedDocumentID("deliverynote123")
+						.setDeliveryNoteReferencedDocumentLineID("deliverypos456")
 						.setDeliveryNoteReferencedDocumentDate(new SimpleDateFormat("dd.MM.yyyy").parse("14.01.2026"))
 					)
 					.addCharge(new Charge(new BigDecimal(0.5)).setReason("quick delivery charge").setTaxPercent(new BigDecimal(16)))
@@ -652,6 +653,7 @@ public class ZF2PushTest extends TestCase {
 		assertTrue(zi.getUTF8().contains(contractID));
 		assertEquals(zi.importedInvoice.getZFItems()[0].getId(), "a123");
 		assertEquals(zi.importedInvoice.getZFItems()[0].getDeliveryNoteReferencedDocumentID(), "deliverynote123");
+		assertEquals(zi.importedInvoice.getZFItems()[0].getDeliveryNoteReferencedDocumentLineID(), "deliverypos456");
 		try {
 			assertEquals(zi.importedInvoice.getZFItems()[0].getDeliveryNoteReferencedDocumentDate(), new SimpleDateFormat("dd.MM.yyyy").parse("14.01.2026"));
 		} catch (ParseException e) {