return 0;
return 0.0;
    public double getServiceExemptionCredits(ExecutionPeriod executionPeriod) {        OccupationPeriod occupationPeriod = executionPeriod.getLessonsPeriod();        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;    }