@Override public boolean assignTeacherToCommissionForThesisDefence( Teacher teacher, ObjectId thesisDefenceId) { ThesisDefence defence = getThesisDefenceById(thesisDefenceId); if (defence != null) { List<ObjectId> commission = defence.getCommissionParticipantIds(); if (commission == null) { commission = new ArrayList<ObjectId>(); } if (!commission.contains(teacher)) { commission.add(teacher.getId()); mongoTemplate.save(defence); return true; } } return false; }