@RequiredArgsConstructor

@RequiredArgsConstructor을 적용하면 fianl이 붙은 필드를 모아서 생성자를 자동으로 만들어준다.

@RequiredArgsConstructor 적용 전

@Component
public class OrderServiceImpl implements OrderService {
    private final MemberRepository memberRepository;
    private final DiscountPolicy discountPolicy;
    
    public OrderServiceImpl(MemberRepository memberRepository, DiscountPolicy discountPolicy) {
        this.memberRepository = memberRepository;
        this.discountPolicy = discountPolicy;
    }
}

@RequiredArgsConstructor 적용 후

@Component
@RequiredArgsConstructor
public class OrderServiceImpl implements OrderService {
    private final MemberRepository memberRepository;
    private final DiscountPolicy discountPolicy;
}

참조
https://www.inflearn.com/course/%EC%8A%A4%ED%94%84%EB%A7%81-%ED%95%B5%EC%8B%AC-%EC%9B%90%EB%A6%AC-%EA%B8%B0%EB%B3%B8%ED%8E%B8