examStudentRoom.setRoom(null);
    public Boolean run(String username, Integer examId) throws FenixServiceException,            ExcepcaoPersistencia {        ISuportePersistente sp = PersistenceSupportFactory.getDefaultPersistenceSupport();        IPersistentStudent persistentStudent = sp.getIPersistentStudent();        IStudent student = persistentStudent.readByUsername(username);        IPersistentExam persistentExam = sp.getIPersistentExam();        IExam exam = (IExam) persistentExam.readByOID(Exam.class, examId, true);        if (student != null && exam != null) {            if (!validUnEnrollment(exam)) {                throw new notAuthorizedServiceDeleteException();            }            IPersistentExamStudentRoom persistentExamStudentRoom = sp.getIPersistentExamStudentRoom();            ExamStudentRoom examStudentRoom = (ExamStudentRoom) persistentExamStudentRoom.readBy(exam                    .getIdInternal(), student.getIdInternal());            if (examStudentRoom != null) {                if (examStudentRoom.getRoom() != null) {                    throw new notAuthorizedServiceDeleteException();                }                examStudentRoom.getExam().getExamStudentRooms().remove(examStudentRoom);                examStudentRoom.getRoom().getExamStudentRooms().remove(examStudentRoom);                examStudentRoom.getStudent().getExamStudentRooms().remove(examStudentRoom);                                examStudentRoom.setExam(null);                examStudentRoom.setRoom(null);                examStudentRoom.setStudent(null);                                sp.getIPersistentExamStudentRoom().deleteByOID(ExamStudentRoom.class,                        examStudentRoom.getIdInternal());            }        }        return new Boolean(true);    }