Add more setter for notes

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

@@ -30,6 +30,12 @@ public class IncludedNote {
   public static IncludedNote taxNote(String content) {
     return new IncludedNote(content, SubjectCode.TXD);
   }
+  public static IncludedNote introductionNote(String content) {
+    return new IncludedNote(content, SubjectCode.ACY);
+  }
+  public static IncludedNote discountBonusNote(String content) {
+    return new IncludedNote(content, SubjectCode.AAK);
+  }
 
   public String getContent() {
     return content;

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

@@ -699,7 +699,7 @@ public class Invoice implements IExportableTransaction {
    * @param content freeform UTF8 plain text
    * @return fluent setter
    */
-  public Invoice regulatoryNote(String content) {
+  public Invoice addRegulatoryNote(String content) {
     if (includedNotes == null) {
       includedNotes = new ArrayList<>();
     }
@@ -713,7 +713,7 @@ public class Invoice implements IExportableTransaction {
    * @param content freeform UTF8 plain text
    * @return fluent setter
    */
-  public Invoice legalNote(String content) {
+  public Invoice addLegalNote(String content) {
     if (includedNotes == null) {
       includedNotes = new ArrayList<>();
     }
@@ -727,7 +727,7 @@ public class Invoice implements IExportableTransaction {
    * @param content freeform UTF8 plain text
    * @return fluent setter
    */
-  public Invoice customsNote(String content) {
+  public Invoice addCustomsNote(String content) {
     if (includedNotes == null) {
       includedNotes = new ArrayList<>();
     }
@@ -741,7 +741,7 @@ public class Invoice implements IExportableTransaction {
    * @param content freeform UTF8 plain text
    * @return fluent setter
    */
-  public Invoice sellerNote(String content) {
+  public Invoice addSellerNote(String content) {
     if (includedNotes == null) {
       includedNotes = new ArrayList<>();
     }
@@ -755,7 +755,7 @@ public class Invoice implements IExportableTransaction {
    * @param content freeform UTF8 plain text
    * @return fluent setter
    */
-  public Invoice taxNote(String content) {
+  public Invoice addTaxNote(String content) {
     if (includedNotes == null) {
       includedNotes = new ArrayList<>();
     }
@@ -763,6 +763,33 @@ public class Invoice implements IExportableTransaction {
     return this;
   }
   
+   /**
+   * adds a free text paragraph, which will become an includedNote element with explicit 
+   * subjectCode {@link SubjectCode#ACY}
+   * @param content freeform UTF8 plain text
+   * @return fluent setter
+   */
+  public Invoice addIntroductionNote(String content) {
+    if (includedNotes == null) {
+      includedNotes = new ArrayList<>();
+    }
+    includedNotes.add(IncludedNote.introductionNote(content));
+    return this;
+  }  
+   /**
+   * adds a free text paragraph, which will become an includedNote element with explicit 
+   * subjectCode {@link SubjectCode#AAK}
+   * @param content freeform UTF8 plain text
+   * @return fluent setter
+   */
+  public Invoice addDiscountBonusNote(String content) {
+    if (includedNotes == null) {
+      includedNotes = new ArrayList<>();
+    }
+    includedNotes.add(IncludedNote.discountBonusNote(content));
+    return this;
+  }
+  
 	@Override
 	public String getSpecifiedProcuringProjectID() {
 		return specifiedProcuringProjectID;

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

@@ -27,5 +27,13 @@ public enum SubjectCode {
   /**
    * Customs information
    */
-  CUS
+  CUS,
+  /**
+   * introduction
+   */
+  ACY,
+  /**
+   * Discount and bonus agreements
+   */
+  AAK
 }

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

@@ -41,6 +41,7 @@ import org.dom4j.DocumentHelper;
 import org.dom4j.io.OutputFormat;
 import org.dom4j.io.XMLWriter;
 import org.mustangproject.FileAttachment;
+import org.mustangproject.SubjectCode;
 import org.mustangproject.XMLTools;
 import org.mustangproject.ZUGFeRD.model.DocumentCodeTypeConstants;
 
@@ -753,13 +754,17 @@ public class ZUGFeRD2PullProvider implements IXMLProvider {
     if (trans.rebateAgreementExists()) {
       notes.append("<ram:IncludedNote><ram:Content>")
           .append("Es bestehen Rabatt- und Bonusvereinbarungen.</ram:Content>")
-          .append("<ram:SubjectCode>AAK</ram:SubjectCode></ram:IncludedNote>");
+          .append("<ram:SubjectCode>")
+          .append(SubjectCode.AAK)
+          .append("</ram:SubjectCode></ram:IncludedNote>");
     }
     if (trans.getOwnOrganisationFullPlaintextInfo() != null) {
       notes.append("<ram:IncludedNote><ram:Content>")
           .append(XMLTools.encodeXML(trans.getOwnOrganisationFullPlaintextInfo()))
           .append("</ram:Content>")
-          .append("<ram:SubjectCode>REG</ram:SubjectCode></ram:IncludedNote>");
+          .append("<ram:SubjectCode>")
+          .append(SubjectCode.REG)
+          .append("</ram:SubjectCode></ram:IncludedNote>");
     }
     if (trans.getSubjectNote() != null) {
       notes.append("<ram:IncludedNote><ram:Content>")