OccupationPeriod occupationPeriod = getLessonsPeriod(executionPeriod);
OccupationPeriod occupationPeriod = executionPeriod.getLessonsPeriod();
    public double getServiceExemptionCredits(ExecutionPeriod executionPeriod) {                OccupationPeriod occupationPeriod = getLessonsPeriod(executionPeriod);        if (occupationPeriod == null) {            return 0;        }        List<TeacherServiceExemption> serviceExemptions = getServiceExemptionsWithoutMedicalSituations(occupationPeriod                .getStartYearMonthDay(), occupationPeriod.getEndYearMonthDay());        if (!serviceExemptions.isEmpty()) {            TeacherServiceExemption teacherServiceExemption = chooseOneServiceExemption(serviceExemptions, occupationPeriod);            return getCreditsForServiceExemption(executionPeriod, teacherServiceExemption, occupationPeriod);        }        return 0.0;    }    