protected void recalculateField(PDAcroFormField source, PDAcroFormField field) {
   String fieldValue = field.getValueString();
   TriggerEvent trigger = triggerCalculate(field, fieldValue, source);
   if (trigger.getRc()) {
     String newFieldValue = trigger.getValueString();
     if ((newFieldValue != null) && !newFieldValue.equals(fieldValue)) {
       field.setValueString(trigger.getValueString());
       createAppearance(field);
     }
   }
 }