用Jackson序列化Map <Date,String>

{
  "2022-01-01T00:00:00.000+0000": "value1"
}

import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

public class JacksonDemo {
    public static void main(String[] args) throws Exception {
        ObjectMapper objectMapper = new ObjectMapper();
        Map<Date, String> map = new HashMap<>();
        map.put(new Date(), "value1");
        String jsonString = objectMapper.writeValueAsString(map);
        System.out.println(jsonString);
    }
}