Retrofit parse error body sample

MainActivity.java

package com.mrezanasirloo.retrofiterrorhandling;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

import java.io.IOException;
import java.lang.annotation.Annotation;

import okhttp3.ResponseBody;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Converter;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
import retrofit2.http.Body;
import retrofit2.http.POST;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = MainActivity.class.getSimpleName();
    private Retrofit retrofit;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        retrofit = new Retrofit.Builder()
                .addConverterFactory(GsonConverterFactory.create())
                .baseUrl("https://reqres.in/api/")
                .build();
        ReqresApi api = retrofit.create(ReqresApi.class);

        api.login(new BodyModel("peter@klaven"))
                .enqueue(new Callback<ExpectedModel>() {
                    @Override
                    public void onResponse(@NonNull Call<ExpectedModel> call, @NonNull Response<ExpectedModel> response) {
                        Log.d(TAG, "onResponse() called with: call = [" + call + "], response = [" + response + "]");
                        if (response.isSuccessful()) {
                            //Do what you got to do
                        } else {
                            Converter<ResponseBody, ErrorModel> converter = MainActivity.this.retrofit.responseBodyConverter(ErrorModel.class, new Annotation[0]);
                            ErrorModel errorModel = null;
                            try {
                                errorModel = converter.convert(response.errorBody());
                                Toast.makeText(MainActivity.this, errorModel.toString(), Toast.LENGTH_SHORT).show();
                            } catch (IOException e) {
                                e.printStackTrace();
                            }
                        }

                    }

                    @Override
                    public void onFailure(@NonNull Call<ExpectedModel> call, @NonNull Throwable t) {
                        Log.d(TAG, "onFailure() called with: call = [" + call + "], t = [" + t + "]");
                    }
                });
    }

    class ExpectedModel {

    }

    public class ErrorModel {

        @SerializedName("error")
        @Expose
        public String error;

        @Override
        public String toString() {
            return "ErrorModel{" +
                    "error='" + error + '\'' +
                    '}';
        }
    }

    public class BodyModel {

        @SerializedName("email")
        @Expose
        public String email;

        public BodyModel(String email) {
            this.email = email;
        }
    }

    interface ReqresApi {
        @POST("login")
        Call<ExpectedModel> login(@Body BodyModel body);
    }
}