MemberApiControllerv1질문있습니다.

package jpabook.jpashop.domains;

import com.fasterxml.jackson.annotation.JsonIgnore;
import jakarta.persistence.*;
import lombok.Getter;
import lombok.Setter;

//import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;

@Entity
@Getter
@Setter
public class Member {

    @Id
    @GeneratedValue
    @Column(name = "member_id")
    private Long id;

    private String name;

    @Embedded
    private Address address;

    @JsonIgnore
    @OneToMany(mappedBy = "member")
    private List<Order> orders = new ArrayList<>();
}

@RequiredArgsConstructor
@RestController
public class MemberApiController {
    private final MemberService memberService;
    @PostMapping()
    public CreateMemberResponse saveMemberV1(@RequestBody @Valid Member member){//jason데이터를 멤버로 쫙 바꿔줌(맵핑해줌_))
        Long id = memberService.join(member);
        return new CreateMemberResponse(id);
    }

    @Data
    static class CreateMemberResponse{
        private Long id;

        public CreateMemberResponse(Long id) {
            this.id = id;
        }


    }

}

1. class Member에 getter,setter가 들어가 있는데 class MemberApiController에 왜 아래처럼 생성자를 생성해주는건가요?

        public CreateMemberResponse(Long id) {
            this.id = id;
        }

2. save함수는 아래에도 있는데 굳이 saveMemberV1 할 이유가 있나요? 혹시 api를 만들때는 엔티티매니저가 사용이 안되나요?

public class MemberRepository {
    //    @PersistenceContext//스프링이 엔티티 매니저를 만들면서 주입시켜주게 됨.
    private final EntityManager em;

    public void save(Member member) {
        em.persist(member);
    }

3 해당 강의에서 중간중간에 엔티티를 변경 즉 name->username으로 변경 시 api오류가나온다고 하셨는데요. 그런데 아래 코드 v1버전 중 CreateMemberResponse 매개변수에Member member가 주어지는데요. 생성자인 CreateMemberResponse(Long id)가 id만 받아와 지는데, 이 id가 (name이 아닌 id만 받아옴) member의 id기준으로 member의 전체 객체가 받아와져서 그러는건가요?

package jpabook.jpashop.api;

import jakarta.validation.Valid;
import jpabook.jpashop.Service.MemberService;
import jpabook.jpashop.domains.Member;
import lombok.Data;
import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;


@RequiredArgsConstructor
@RestController
public class MemberApiController {
    private final MemberService memberService;
    @PostMapping("/api/v1/members")
    public CreateMemberResponse saveMemberV1(@RequestBody @Valid Member member){//jason데이터를 멤버로 쫙 바꿔줌(맵핑해줌_))
        Long id = memberService.join(member);
        return new CreateMemberResponse(id);
    }

    @PostMapping("/api/v2/members")
    public CreateMemberResponse saveMemberV2(@RequestBody @Valid CreateMemberRequest request){
        Member member=new Member();
        member.setName(request.getName());
        Long id=memberService.join(member);
        return new CreateMemberResponse(id);
    }

    @Data
    static class CreateMemberRequest{
        private String name;//<-강의 중반주에 adreess넣을지 말지 하는 부분이 있었는데요. 만약 adress를 넣는다면,  member.setadress(request.getadress());를 안넣게되면 에러인가요?
    }

    @Data
    static class CreateMemberResponse{
        private Long id;

        public CreateMemberResponse(Long id) {
            this.id = id;
        }


    }

}

.