List executionPeriods = readAllExecutionPeriod();
Collection executionPeriods = readAll(ExecutionPeriod.class);
    public IExecutionPeriod readActualExecutionPeriod() throws ExcepcaoPersistencia {        List executionPeriods = readAllExecutionPeriod();           for (Iterator iter = executionPeriods.iterator(); iter.hasNext();) {            ExecutionPeriod element = (ExecutionPeriod) iter.next();            if(element.getState().equals(PeriodState.CURRENT))                return element;        }                                      return null;    }