public CheckboxAnswer getAnswerByQuestionId(long questionId) {
        if (!checkboxAnswers.containsKey(questionId)) {
            throw new MissingCheckboxAnswerForQuestionException(questionId);
        }
        return checkboxAnswers.get(questionId);
    }
@Test
    void 질문에_해당하는_답변이_없으면_예외를_발생한다() {
        // given
        CheckboxAnswers checkboxAnswers = new CheckboxAnswers(List.of(new CheckboxAnswer(1, List.of(1L))));

        // when, then
        assertThatThrownBy(() -> checkboxAnswers.getAnswerByQuestionId(2))
                .isInstanceOf(MissingCheckboxAnswerForQuestionException.class);
    }