Как я могу исправить эту функцию, когда я получаю нулевые значения от модернизации?

Question

Я пытаюсь получить некоторые значения от модернизации. Я получаю ответ 200, но когда я пытаюсь распечатать эту информацию, я получаю on a null object reference. Я не понимаю этого, потому что я получаю ответ для ввода OnSuccessfull, но, наконец, при печати данных выдает ошибку. Это метод:

  public void getAllParticipantByGroup(String id_group){
        Call<ParticipantResponse> call = APIService.getParticipantsByGroup(id_group);
        call.enqueue(new Callback<ParticipantResponse>() {
            @Override
            public void onResponse(Call<ParticipantResponse> call, Response<ParticipantResponse> response) {
                if (response.isSuccessful()) {
                    participantResponse = response.body();
Log.d("VALUE",String.valueOf(participantResponse.getParticipant().getId()));

                    Log.d("RESPONSE_SUCCESS", "Everything All right");

                }
            }

            @Override
            public void onFailure(Call<ParticipantResponse> call, Throwable t) {
                Log.d("RESPONSE_FAILURE", String.valueOf(t));
            }
        });
    }

Это ОК.

2020-04-22 16:31:20.594 6001-6033/com.example.karate_manager D/OkHttp: --> GET http://111.111.11.1/trabajos/api-manager-karate/karate-manager-api-laravel/public/api/participant/getall/4
2020-04-22 16:31:20.594 6001-6033/com.example.karate_manager D/OkHttp: --> END GET
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: <-- 200 OK http://111.111.11.1/trabajos/api-manager-karate/karate-manager-api-laravel/public/api/participant/getall/4 (138ms)
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: Date: Wed, 22 Apr 2020 14:31:20 GMT
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: Server: Apache/2.4.38 (Win64) OpenSSL/1.1.1b PHP/7.3.3
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: X-Powered-By: PHP/7.3.3
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: Cache-Control: no-cache, private
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: X-RateLimit-Limit: 60
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: X-RateLimit-Remaining: 56
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: Content-Length: 1376
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: Keep-Alive: timeout=5, max=98
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: Connection: Keep-Alive
2020-04-22 16:31:20.733 6001-6033/com.example.karate_manager D/OkHttp: Content-Type: application/json
2020-04-22 16:31:20.734 6001-6033/com.example.karate_manager D/OkHttp: {"code":200,"participants":[{RESPOSE ARRAY"}
2020-04-22 16:31:20.734 6001-6033/com.example.karate_manager D/OkHttp: <-- END HTTP (1376-byte body)
2020-04-22 16:31:20.790 6001-6001/com.example.karate_manager E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.karate_manager, PID: 6001
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String com.example.karate_manager.Models.ParticipantModel.Participant.getId()' on a null object reference
        at com.example.karate_manager.Fragments.ScoringFragment$1.onResponse(ScoringFragment.java:63)
        at ...

Это участникResponse

public class ParticipantResponse {

    private float code;
    private Participant participant;
    private ArrayList<Participant > participants = new ArrayList <> ();
    private ArrayList<Karateka > karateka = new ArrayList <> ();
    private String msg;

    public float getCode() {
        return code;
    }

    public void setCode(float code) {
        this.code = code;
    }

    public Participant getParticipant() {
        return participant;
    }

    public void setParticipant(Participant participant) {
        this.participant = participant;
    }

    public ArrayList<Karateka> getKarateka() {
        return karateka;
    }

    public void setKarateka(ArrayList<Karateka> karateka) {
        this.karateka = karateka;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public ParticipantResponse(float code, Participant participant, ArrayList<Karateka> karateka, String msg) {
        this.code = code;
        this.participant = participant;
        this.karateka = karateka;
        this.msg = msg;
    }

    public ParticipantResponse(float code, ArrayList<Participant> participants, String msg) {
        this.code = code;
        this.participants = participants;
        this.msg = msg;
    }


}

А это модель участника

public class Participant {

    ArrayList<Participant> scoring = new ArrayList<Participant>();

    public ArrayList<Participant> getScoring() {
        return scoring;
    }

    public Participant (){

    }

    @SerializedName("name")
    private String name;

    @SerializedName("photo_profile")
    private String photo_profile;

    @SerializedName("id_user")
    private float id_user;

    @SerializedName("id_group")
    private String id_group;

    @SerializedName("admin_user_group")
    private String admin_user_group;

    @SerializedName("points")
    private float points;

    @SerializedName("own_budget")
    private float own_budget;

    @SerializedName("updated_at")
    private String updated_at = null;

    @SerializedName("created_at")
    private String created_at;

    @SerializedName("id")
    private String id;

    public Participant(float id_user, String id_group, String admin_user_group, float points, float own_budget, String updated_at, String created_at, String id) {
        this.id_user = id_user;
        this.id_group = id_group;
        this.admin_user_group = admin_user_group;
        this.points = points;
        this.own_budget = own_budget;
        this.updated_at = updated_at;
        this.created_at = created_at;
        this.id = id;
    }

    public void setId_user(float id_user) {
        this.id_user = id_user;
    }



    public void setAdmin_user_group(String admin_user_group) {
        this.admin_user_group = admin_user_group;
    }

    public void setPoints(float points) {
        this.points = points;
    }

    public void setOwn_budget(float own_budget) {
        this.own_budget = own_budget;
    }

    public void setUpdated_at(String updated_at) {
        this.updated_at = updated_at;
    }

    public void setCreated_at(String created_at) {
        this.created_at = created_at;
    }

    public void setId(String id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setPhoto_profile(String photo_profile) {
        this.photo_profile = photo_profile;
    }

    public void setId_group(String id_group) {
        this.id_group = id_group;
    }

    public float getId_user() {
        return id_user;
    }

    public String getName() {
        return name;
    }

    public String getPhoto_profile() {
        return photo_profile;
    }

    public String getId_group() {
        return id_group;
    }

    public String getAdmin_user_group() {
        return admin_user_group;
    }

    public float getPoints() {
        return points;
    }

    public float getOwn_budget() {
        return own_budget;
    }

    public String getUpdated_at() {
        return updated_at;
    }

    public String getCreated_at() {
        return created_at;
    }

    public String getId() {
        return id;
    }
}

Это ответ в Почтальон:

{
    "code": 200,
    "participants": [
        {
            "id": 6,
            "own_budget": -7992,
            "points": 0,
            "admin_user_group": 1,
            "id_user": 1,
            "id_group": 4,
            "created_at": "2020-04-07 19:13:48",
            "updated_at": "2020-04-12 14:26:46",
            "email": "pedor@gmail.com",
            "name": "pedro",
            "photo_profile": null
        },
        {
            "id": 7,
            "own_budget": 10000,
            "points": 0,
            "admin_user_group": 0,
            "id_user": 3,
            "id_group": 4,
            "created_at": "2020-04-07 19:14:18",
            "updated_at": "2020-04-07 19:14:18",
            "email": "javier@gmail.com",
            "name": "javier",
            "photo_profile": null
        },
        {
            "id": 11,
            "own_budget": 10000,
            "points": 0,
            "admin_user_group": 0,
            "id_user": 5,
            "id_group": 4,
            "created_at": "2020-04-13 09:02:44",
            "updated_at": "2020-04-13 09:02:44",
            "email": "ernesto@gmail.com",
            "name": "ernesto",
            "photo_profile": null
        },
        {
            "id": 20,
            "own_budget": 10000,
            "points": 0,
            "admin_user_group": 0,
            "id_user": 4,
            "id_group": 4,
            "created_at": "2020-04-13 09:49:40",
            "updated_at": "2020-04-13 09:49:40",
            "email": "pepe@gmail.com",
            "name": "pepe",
            "photo_profile": null
        },
        {
            "id": 63,
            "own_budget": 10000,
            "points": 0,
            "admin_user_group": 0,
            "id_user": 2,
            "id_group": 4,
            "created_at": "2020-04-19 15:01:49",
            "updated_at": "2020-04-19 15:01:49",
            "email": "aitor@gmail.com",
            "name": "aitor",
            "photo_profile": null
        },
        {
            "id": 68,
            "own_budget": 10000,
            "points": 0,
            "admin_user_group": 0,
            "id_user": 17,
            "id_group": 4,
            "created_at": "2020-04-21 15:03:46",
            "updated_at": "2020-04-21 15:03:46",
            "email": "hulk@gmail.com",
            "name": "Hulk",
            "photo_profile": null
        }
    ],
    "msg": "Get all participants by group"
}