Add invoiceReferencedIssueDate

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

@@ -46,13 +46,13 @@ public class Invoice implements IExportableTransaction {
 	protected Date detailedDeliveryDateStart = null;
 	protected Date detailedDeliveryPeriodEnd = null;
 
-	protected ArrayList<IZUGFeRDAllowanceCharge> Allowances = new ArrayList<IZUGFeRDAllowanceCharge>(),
-			Charges = new ArrayList<IZUGFeRDAllowanceCharge>(), LogisticsServiceCharges = new ArrayList<IZUGFeRDAllowanceCharge>();
+	protected ArrayList<IZUGFeRDAllowanceCharge> Allowances = new ArrayList<>(),
+			Charges = new ArrayList<>(), LogisticsServiceCharges = new ArrayList<>();
 	protected IZUGFeRDPaymentTerms paymentTerms = null;
-
+  private Date invoiceReferencedIssueDate;
 
   public Invoice() {
-		ZFItems = new ArrayList<IZUGFeRDExportableItem>();
+		ZFItems = new ArrayList<>();
 		setCurrency("EUR");
 	}
 
@@ -246,7 +246,17 @@ public class Invoice implements IExportableTransaction {
 		return invoiceReferencedDocumentID;
 	}
 
-	@Override
+  @Override
+  public Date getInvoiceReferencedIssueDate() {
+    return invoiceReferencedIssueDate;
+  }
+
+  public Invoice setInvoiceReferencedIssueDate(Date issueDate) {
+	  this.invoiceReferencedIssueDate = issueDate;
+	  return this;
+  }
+  
+  @Override
 	public String getBuyerOrderReferencedDocumentIssueDateTime() {
 		return buyerOrderReferencedDocumentIssueDateTime;
 	}

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

@@ -424,6 +424,7 @@ public interface IExportableTransaction  {
 		return null;
 	}
 
+  default Date getInvoiceReferencedIssueDate(){return null;}
 	/**
 	 * get the issue timestamp of the BuyerOrderReferencedDocument, which sits in the ApplicableSupplyChainTradeAgreement
 	 *

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

@@ -631,8 +631,13 @@ public class ZUGFeRD2PullProvider implements IXMLProvider {
 		if (trans.getInvoiceReferencedDocumentID() != null) {
 			xml = xml + "   <ram:InvoiceReferencedDocument>\n"
 					+ "       <ram:IssuerAssignedID>"
-					+ XMLTools.encodeXML(trans.getInvoiceReferencedDocumentID()) + "</ram:IssuerAssignedID>\n"
-					+ "   </ram:InvoiceReferencedDocument>\n";
+					+ XMLTools.encodeXML(trans.getInvoiceReferencedDocumentID()) + "</ram:IssuerAssignedID>\n";
+			if(trans.getInvoiceReferencedIssueDate()!= null){
+				xml += "<ram:FormattedIssueDateTime>" 
+				+ zugferdDateFormat.format(trans.getInvoiceReferencedIssueDate())
+				+ "</ram:FormattedIssueDateTime>\n";
+			}
+			xml += "   </ram:InvoiceReferencedDocument>\n";
 		}
 
 		xml = xml + "		</ram:ApplicableHeaderTradeSettlement>\n";