responsibleFor.setExecutionCourse(null);
    private void removeResponsibleFors(ITeacher teacher, List responsabilitiesToRemove,            IPersistentResponsibleFor responsibleForDAO, IPersistentExecutionCourse executionCourseDAO)            throws ExcepcaoPersistencia {        if (!responsabilitiesToRemove.isEmpty()) {            List responsibleFors = responsibleForDAO.readByTeacherAndExecutionCourseIds(teacher                    .getIdInternal(), responsabilitiesToRemove);            for (int i = 0; i < responsibleFors.size(); i++) {                IResponsibleFor responsibleFor = (IResponsibleFor) responsibleFors.get(i);                responsibleFor.getExecutionCourse().getResponsibleTeachers().remove(responsibleFor);                responsibleFor.setExecutionCourse(null);                responsibleFor.getTeacher().getAssociatedResponsibles().remove(responsibleFor);                responsibleFor.setTeacher(null);                responsibleForDAO.deleteByOID(ResponsibleFor.class, responsibleFor.getIdInternal());            }        }    }