API Parameter Validation 체크 비교 (@NotNull, @NotEmpty, @NotBlank) @NotNull 모든 데이터 타입에 대해 null체크 public class UserNotNull { @NotNull(message = "Name may not be null") private String name; // standard constructors / getters / toString } @NotEmpty CharSequence (length of character sequence is evaluated) Collection (collection size is evaluated) Map (map size is evaluated) Array (array length is evalu..