updated javadocs

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

@@ -478,7 +478,9 @@ public class Invoice implements IExportableTransaction {
 	}
 
 	/***
-	 * for currency rounding differences to 5ct e.g. in Netherlands ("Rappenrundung")
+	 * set the cent e.g. to reach the next 5ct mark for currencies in certain countries
+	 * e.g. in the Netherlands ("Rappenrundung")
+	 * @param amount
 	 * @return fluent setter
 	 */
 	public Invoice setRoundingAmount(BigDecimal amount) {
@@ -543,8 +545,8 @@ public class Invoice implements IExportableTransaction {
 
 	/***
 	 * this is wrong and only used from jackson
-	 * @param iza
-	 * @return
+	 * @param iza the Array of allowances/charges
+	 * @return fluent setter
 	 */
 	public Invoice setZFAllowances(Allowance[] iza) {
 		Allowances=new ArrayList<>();
@@ -567,8 +569,8 @@ public class Invoice implements IExportableTransaction {
 
 	/***
 	 * this is wrong and only used from jackson
-	 * @param iza
-	 * @return
+	 * @param iza the array of charges
+	 * @return fluent setter
 	 */
 	public Invoice setZFCharges(Charge[] iza) {
 		Charges=new ArrayList<>();