如何将具有类似密钥的List<Map<String，String>>转换为Map<String，List<String>>？

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class ListMapConverter {
    public static Map<String, List<String>> convert(List<Map<String, String>> listMap) {
        Map<String, List<String>> resultMap = new HashMap<>();

        for (Map<String, String> map : listMap) {
            for (Map.Entry<String, String> entry : map.entrySet()) {
                String key = entry.getKey();
                String value = entry.getValue();

                if (resultMap.containsKey(key)) {
                    resultMap.get(key).add(value);
                } else {
                    List<String> valueList = new ArrayList<>();
                    valueList.add(value);
                    resultMap.put(key, valueList);
                }
            }
        }

        return resultMap;
    }

    public static void main(String[] args) {
        List<Map<String, String>> listMap = new ArrayList<>();
        Map<String, String> map1 = new HashMap<>();
        map1.put("key1", "value1");
        map1.put("key2", "value2");
        listMap.add(map1);
        Map<String, String> map2 = new HashMap<>();
        map2.put("key1", "value3");
        map2.put("key3", "value4");
        listMap.add(map2);

        Map<String, List<String>> resultMap = convert(listMap);
        System.out.println(resultMap);
    }
}

{key1=[value1, value3], key2=[value2], key3=[value4]}