updated some javadoc

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

@@ -7,14 +7,35 @@ import org.mustangproject.ZUGFeRD.IZUGFeRDExportableItem;
 
 import java.math.BigDecimal;
 
+/***
+ * Absolute and relative charges for document and item level
+ */
 public class Charge implements IZUGFeRDAllowanceCharge {
 
+	/**
+	 * the percentage, null if not relative at all
+	 */
 	protected BigDecimal percent = null;
+	/**
+	 * the absolute value if not percentage
+	 */
 	protected BigDecimal totalAmount;
+	/**
+	 * the tax rate the charge belongs to
+	 */
 	protected BigDecimal taxPercent;
+	/**
+	 * a simple human readable description
+	 */
 	protected String reason;
+	/**
+	 * the category ID why this charge has been applied
+	 */
 	protected String categoryCode;
 
+	/***
+	 * Bean connstructor
+	 */
 	public Charge() {
 		taxPercent=BigDecimal.ZERO;
 	}
@@ -28,16 +49,31 @@ public class Charge implements IZUGFeRDAllowanceCharge {
 	}
 
 
+	/***
+	 * sets the total amount to be changed to, e.g. if not specified via constructor
+	 * @param totalAmount 2 decimal money amount
+	 * @return fluid setter
+	 */
 	public Charge setTotalAmount(BigDecimal totalAmount) {
 		this.totalAmount = totalAmount;
 		return this;
 	}
 
+	/***
+	 * if relative charge: percent to increase the item
+	 * @param percent as bigdecimal
+	 * @return fluid setter
+	 */
 	public Charge setPercent(BigDecimal percent) {
 		this.percent = percent;
 		return this;
 	}
 
+	/***
+	 * charges can be applied to VAT items, in which case they take the same VAT rate
+	 * @param taxPercent the tax percentage on the charge
+	 * @return fluid setter
+	 */
 	public Charge setTaxPercent(BigDecimal taxPercent) {
 		this.taxPercent = taxPercent;
 		return this;
@@ -49,6 +85,11 @@ public class Charge implements IZUGFeRDAllowanceCharge {
 		return reason;
 	}
 
+	/***
+	 * Freetext (?) reason for the charge
+	 * @param reason freetext
+	 * @return fluid setter
+	 */
 	public Charge setReason(String reason) {
 		this.reason = reason;
 		return this;
@@ -77,6 +118,12 @@ public class Charge implements IZUGFeRDAllowanceCharge {
 		return taxPercent;
 	}
 
+
+
+	/***
+	 * Always to return true  for IZUGFeRDAllowanceCharge
+	 * @return true since it is supposed to be calculated negatively
+	 */
 	@Override
 	public boolean isCharge() {
 		return true;
@@ -91,6 +138,11 @@ public class Charge implements IZUGFeRDAllowanceCharge {
 	}
 
 
+	/***
+	 * machine readable reason for this allowance/charge
+	 * @param categoryCode usually S
+	 * @return fluid setter
+	 */
 	public Charge setCategoryCode(String categoryCode) {
 		this.categoryCode = categoryCode;
 		return this;