RestClient

public class RestClient {
    private static final String VK_BASE_URL = "https://api.vk.com/method/";

    private Retrofit mRetrofit;

    public RestClient() {

        HttpLoggingInterceptor logging = new HttpLoggingInterceptor();
        logging.setLevel(HttpLoggingInterceptor.Level.BODY);
        OkHttpClient httpClient = new OkHttpClient.Builder().addInterceptor(logging).build();



        mRetrofit = new Retrofit.Builder()
                .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
                .addConverterFactory(GsonConverterFactory.create())
                .baseUrl(VK_BASE_URL)
                .client(httpClient)
                .build();
    }

    public <S> S createService(Class<S> serviceClass) {
        return mRetrofit.create(serviceClass);
    }
}