todo

특정한 조건에서만 notNull처리하도록 하기 @Validated, group 이용

https://okky.kr/article/395164 http://hungry-developer.blogspot.com/2014/06/spring-validated.html

 

array valid안되는 문제

https://stackoverflow.com/questions/28150405/validation-of-a-list-of-objects-in-spring

 

validation 내용잘정리됨

https://medium.com/@gaemi/java-%EC%99%80-spring-%EC%9D%98-validation-b5191a113f5c