Merge pull request #728 from christoph-sommer/t/invoice-set-correction

Invoice setCorrection causes duplicate XML output

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

@@ -158,7 +158,6 @@ public class Invoice implements IExportableTransaction {
 	 */
 	public Invoice setCorrection(String number) {
 		setInvoiceReferencedDocumentID(number);
-		addInvoiceReferencedDocument(new ReferencedDocument(number));
 		documentCode = DocumentCodeTypeConstants.CORRECTEDINVOICE;
 		return this;
 	}