public class ControllerReview implements Callback<List<reviewResult>> {

    public Context context;

    static final String BASE_URL = "http://busboosted.000webhostapp.com/";

    public void start(final Context context, String login, String password, Callback<List<reviewResult>> callback) {
        Gson gson = new GsonBuilder()
                .setLenient()
                .create();

        this.context = context;

        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(BASE_URL)
                .addConverterFactory(GsonConverterFactory.create(gson))
                .build();

        Api gerritAPI = retrofit.create(Api.class);

        Call<List<reviewResult>> call = gerritAPI.getReview();

        call.enqueue(new Callback<List<reviewResult>>() {
            @Override
            public void onResponse(Call<List<reviewResult>> call, Response<List<reviewResult>> response) {
                List<reviewResult> res = response.body();
                res.getReview();//how to get a list?
            }

            @Override
            public void onFailure(Call<List<reviewResult>> call, Throwable t) {

            }
        });


    }