https://velog.io/@wonizizi99/Java-Stream%EB%9E%8C%EB%8B%A4%EC%8B%9D%ED%95%A8%EC%88%98%ED%98%95%EC%9D%B8%ED%84%B0%ED%8E%98%EC%9D%B4%EC%8A%A4
