Как распарсить getUpdates в API telegram на Retrofit2?

помогите распарсить getUpdates на Retrofit2 в API telegram.... суть в том что ссылка парсится, а вот данные приходят NULL....

введите сюда описание ссылки

в MainActivity:

NetworkService.getInstance()
                    .getJSONApi()
                    .operation("result")
                    .enqueue(new Callback<Post>() {
                        @Override
                        public void onResponse(@NonNull Call<Post> call, @NonNull Response<Post> response) {
                            Post post = response.body();

                            Log.v("response1", post.getUpdateId() + " " + post.getId() + " " + post.getMessageId()+ " " + 
                            post.getText());
                        }

                        @Override
                        public void onFailure(@NonNull Call<Post> call, @NonNull Throwable t) {
                            Toast.makeText(MainActivity.this, "Error occurred while getting request!", 
                            Toast.LENGTH_SHORT).show();
                            //textView.append("Error occurred while getting request!");
                            t.printStackTrace();
                        }
                    });

код NetworkService:

public class NetworkService {
    private static NetworkService mInstance;
    private static final String BASE_URL = "https://api.telegram.org";
    private Retrofit mRetrofit;
  public static final String LOGIN_OPERATION = "login";

    private NetworkService() {
        mRetrofit = new Retrofit.Builder()
      .baseUrl(BASE_URL)
      .addConverterFactory(GsonConverterFactory.create())
      .build();

    }

    public static NetworkService getInstance() {
        if (mInstance == null) {
            mInstance = new NetworkService();

      NetworkService.getInstance()
        .getJSONApi()
        .operation("result")
        .enqueue(new Callback<Post>() {

          private Context context;
          @Override
          public void onResponse(@NonNull Call<Post> call, @NonNull Response<Post> response) {
            Post post = response.body();
}
          @Override
          public void onFailure(@NonNull Call<Post> call, @NonNull Throwable t) {
            Toast.makeText(context, "Error occurred while getting request!", Toast.LENGTH_SHORT).show();                        

            t.printStackTrace();
          }
        });
        }
        return mInstance;
    }
  public JSONPlaceHolderApi getJSONApi() {
        return mRetrofit.create(JSONPlaceHolderApi.class);
    }

код JSONPlaceHolderApi :

public interface JSONPlaceHolderApi {

    @POST("/bot1080783949:AAEvVVE_fmiHqBU9Oy_rd2RxTmxdbWQOdAc/getUpdates")
    Call<Post> operation(@Body String request);
}

код Post:

public class Post {
    @SerializedName("update_id")
    @Expose
    private double update_id;

    @SerializedName("message_id")
    @Expose
    private int message_id;

    @SerializedName("id")
    @Expose
    private double id;

    @SerializedName("username")
    @Expose
    private String username;

  @SerializedName("date")
    @Expose
    private double date;

  @SerializedName("text")
    @Expose
    private String text;

    public double getUpdateId() {
        return update_id;
    }
    public void setUpdateId(double update_id) {
        this.update_id = update_id;
    }
    public int getMessageId() {
        return message_id;
    }
    public void setMessageId(int message_id) {
        this.message_id = message_id;
    }
    public double getId() {
        return id;
    }
    public void setId(double id) {
        this.id = id;
    }
    public String getUserName() {
        return username;
    }
    public void setUserName(String username) {
        this.username = username;
    }
  public double getDate() {
        return date;
    }
    public void setDate(double date) {
        this.date = date;
    }
  public String getText() {
        return text;
    }
    public void setText(String text) {
        this.text = text;
    }
}