질문있습니다.

조회한 빈이 모두 필요할 때 List,Map을 이용하는 문제입니다.

package hello.core.autowired;

import hello.core.AutoAppConfig;
import hello.core.discount.DiscountPolicy;
import hello.core.member.Grade;
import hello.core.member.Member;
import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import
org.springframework.context.annotation.AnnotationConfigApplicationContext;
import java.util.List;
import java.util.Map;
import static org.assertj.core.api.Assertions.assertThat;
public class AllBeanTest {
 @Test
 void findAllBean() {
 ApplicationContext ac = new
AnnotationConfigApplicationContext(AutoAppConfig.class, DiscountService.class);
 DiscountService discountService = ac.getBean(DiscountService.class);
 Member member = new Member(1L, "userA", Grade.VIP);
 int discountPrice = discountService.discount(member, 10000, 
"fixDiscountPolicy");
 assertThat(discountService).isInstanceOf(DiscountService.class);
 assertThat(discountPrice).isEqualTo(1000);
 }
 static class DiscountService {
 private final Map<String, DiscountPolicy> policyMap;
 private final List<DiscountPolicy> policies;
 public DiscountService(Map<String, DiscountPolicy> policyMap, 
List<DiscountPolicy> policies) {
 this.policyMap = policyMap;
 this.policies = policies;
 System.out.println("policyMap = " + policyMap);
 System.out.println("policies = " + policies);
 }
 public int discount(Member member, int price, String discountCode) {
 DiscountPolicy discountPolicy = policyMap.get(discountCode);
 System.out.println("discountCode = " + discountCode);
 System.out.println("discountPolicy = " + discountPolicy);
 return discountPolicy.discount(member, price);
 }
 }
}

여기서 policyMap과 List에 주입되는 과정이 이해가 안갑니다. Map은 왜 <String,DiscountPolicy>로 정의했고 List는 <DiscountPolicy>로 정의 했는지, 그리고 여기에 어떻게 Ratediscountpolicy와 Fixdiscountpolicy가 들어갔는지 궁금합니다.