public QuantityRequirement(
     String requirementName, String enterString, String recordName, boolean isOptional) {
   super(requirementName, enterString, recordName, isOptional, true);
   ClientQuantity clientQuantity = new ClientQuantity();
   clientQuantity.setValue(1.0);
   setDefaultValue(clientQuantity);
 }
 @Override
 protected Result onFinish(Context context) {
   ClientQuantity quantity = getValue();
   Unit unit = getRequirement(UNIT).getValue();
   quantity.setUnit(unit == null ? 0 : unit.getID());
   quantity.setValue((Double) getRequirement(VALUE).getValue());
   return null;
 }