我的json文件。。。我确信json中没有错误

{
        "-MHG5VdrTky1GdpmNLHl": {
            "author_id": "data1",
            "create_date": 1600162233475,
            "display_name": "data1",
            "phone_number": "data1"
        },
        "-MHG5Vdsy6Hd1zrcRkmm": {
            "author_id": "data1",
            "create_date": 1600162233475,
            "display_name": "data1",
            "phone_number": "data1"
        },
        "-MHG5Vdsy6Hd1zrcRkmn": {
            "author_id": "data1",
            "create_date": 1600162233475,
            "display_name": "data1",
            "phone_number": "data1"
        }
}

我的json文件大小为1gb。我怎么用那个gson读取这个文件？
我的阅读方法。。

InputStream inputStream = new FileInputStream(path);
                Gson gson = new Gson();
                JsonReader reader = new JsonReader(new InputStreamReader(inputStream, StandardCharsets.UTF_8));
                List<ContactList> contactListList = new ArrayList<>();
                reader.beginObject();
                while (reader.hasNext()) {
                    ContactList cts = gson.fromJson(reader, ContactList.class);
    //                contactListList.add(cts);
                }
                reader.endArray();
                reader.close();

我得到的错误：：=>java.lang.illegalstateexception:应为begin\u对象，但名称位于第1行第3列路径$。
我的contactlist类无法读取对象。

public class ContactList {

        private String author_id;
        private String display_name;
        private String phone_number;
        private long create_date;

        public ContactList(){}

        public ContactList(String author_id, String display_name, String phone_number, long create_date) {
            this.author_id = author_id;
            this.display_name = display_name;
            this.phone_number = phone_number;
            this.create_date = create_date;
        }

        public String getAuthor_id() {
            return author_id;
        }

        public void setAuthor_id(String author_id) {
            this.author_id = author_id;
        }

        public String getDisplay_name() {
            return display_name;
        }

        public void setDisplay_name(String display_name) {
            this.display_name = display_name;
        }

        public String getPhone_number() {
            return phone_number;
        }

        public void setPhone_number(String phone_number) {
            this.phone_number = phone_number;
        }

        public long getCreate_date() {
            return create_date;
        }

        public void setCreate_date(long create_date) {
            this.create_date = create_date;
        }
    }