if (executionPeriod.getState() != PeriodState.CLOSED) {
if (executionPeriod.getState().equals(PeriodState.CLOSED)) {
    public static List<ExecutionPeriod> readNotClosedExecutionPeriods() {        final List<ExecutionPeriod> result = new ArrayList<ExecutionPeriod>();        for (final ExecutionPeriod executionPeriod : RootDomainObject.getInstance()                .getExecutionPeriodsSet()) {            if (executionPeriod.getState() != PeriodState.CLOSED) {                result.add(executionPeriod);            }        }        return result;    }