我想要将MultivaluedMap<String，String>标头转换为Map<String，List<String>>

import javax.ws.rs.core.MultivaluedMap;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MultivaluedMapConverter {
    public static Map<String, List<String>> convert(MultivaluedMap<String, String> multivaluedMap) {
        Map<String, List<String>> resultMap = new HashMap<>();

        for (Map.Entry<String, List<String>> entry : multivaluedMap.entrySet()) {
            String key = entry.getKey();
            List<String> values = entry.getValue();

            if (resultMap.containsKey(key)) {
                resultMap.get(key).addAll(values);
            } else {
                resultMap.put(key, new ArrayList<>(values));
            }
        }

        return resultMap;
    }
}