Retrofit with Interceptor and Authenticator.
/**
* Init Retrofit
*/
private void initRetrofit() {
mOkHttpClient = new OkHttpClient.Builder()
.addInterceptor(new AuthenticationInterceptor())
.authenticator(new TokenAuthenticator())
.build();
// Create Gson instance to serialize Nulls
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.serializeNulls();
Gson gson = gsonBuilder.create();
mRetrofit = new Retrofit.Builder()
.baseUrl(BuildConfig.APP_API_URL)
.addConverterFactory(GsonConverterFactory.create(gson))
.client(mOkHttpClient)
.build();
}