为什么改造请求体不能将JSON (GSON)日期格式转换成java对象？

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonDeserializer;

import java.lang.reflect.Type;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Main {
    public static void main(String[] args) {
        String json = "{\"date\": \"2022-01-01 12:00:00\"}";

        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.registerTypeAdapter(Date.class, new DateDeserializer());
        Gson gson = gsonBuilder.create();

        MyObject myObject = gson.fromJson(json, MyObject.class);
        System.out.println(myObject.getDate()); // 输出：Sat Jan 01 12:00:00 CST 2022
    }
}

class MyObject {
    private Date date;

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }
}

class DateDeserializer implements JsonDeserializer<Date> {
    private DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    @Override
    public Date deserialize(com.google.gson.JsonElement jsonElement, Type typeOF,
                            com.google.gson.JsonDeserializationContext context) {
        try {
            return dateFormat.parse(jsonElement.getAsString());
        } catch (ParseException e) {
            return null;
        }
    }
}