Set<Unit> allActiveSubUnits = new HashSet<Unit>();
List<Unit> allActiveSubUnits = new ArrayList<Unit>();
    public List<Unit> getActiveSubUnits(Date currentDate) {        Set<Unit> allActiveSubUnits = new HashSet<Unit>();        for (Unit subUnit : this.getSubUnits()) {            readAndSaveActiveSubUnits(subUnit, allActiveSubUnits, currentDate);        }        return new ArrayList<Unit>(allActiveSubUnits);    }