规避Variable used in lambda expression should be final or effectively final而引发了方法参数值拷贝的问题

package com.lingyejun.dating.chap11.toutiao;

import java.util.*;
import java.util.stream.Collectors;

public class StreamMapCopy {

    public static List<Phone> initPhoneList() {
        List<Phone> phones = new ArrayList<>();
        Phone phone1 = new Phone(1, "iPhone 11 Pro", "银色", "64GB", 8699);
        Phone phone2 = new Phone(2, "iPhone 11 Pro", "银色", "64GB", 8700);
        Phone phone3 = new Phone(3, "iPhone 11 Pro Max", "银色", "64GB", 8900);

        phones.add(phone1);
        phones.add(phone2);
        phones.add(phone3);

        return phones;
    }

    public static void main(String[] args) {

        List<String> queryPhoneNameList = Arrays.asList("iPhone 11 Pro", "HuaWei", "Oppo", "Vivo");

        Map<String, List<Phone>> otherMap = new HashMap<>();

        if (queryPhoneNameList.size() > 0) {

            Map<String, List<Phone>> phoneMap = initPhoneList().stream()
                    .filter(a -> queryPhoneNameList.contains(a.getProductName()))
                    .collect(Collectors.groupingBy(Phone::getProductName));

            // 这种写法下面的forEach循环中使用到的otherMap编译不过去，
            // Variable used in lambda expression should be final or effectively final
            //otherMap = phoneMap;

            // 将逻辑放到方法中可以绕过此逻辑
            copyMap(otherMap, phoneMap);

        }

        queryPhoneNameList.forEach(queryPhoneName -> {
            otherMap.get(queryPhoneName);
        });

    }

    private static void copyMap(Map<String, List<Phone>> sourceMap, Map<String, List<Phone>> targetMap) {
        // 方法参数是值传递，故这种赋值是不会生效的
        targetMap = sourceMap;
        // 改为下面的方式就可以了
        targetMap.putAll(sourceMap);
    }
}

Variable used in lambda expression should be final or effectively final

    private static void copyMap(Map<String, List<Phone>> sourceMap, Map<String, List<Phone>> targetMap) {
        targetMap = sourceMap;
    }

    private static void copyMap(Map<String, List<Phone>> sourceMap, Map<String, List<Phone>> targetMap) {
        targetMap.putAll(sourceMap);
    }