Api Zilliqa getballance example

public class App {
    public static void main(String[] args) throws IOException {
        HttpProvider client = new HttpProvider("https://api.zilliqa.com");
        Rep<HttpProvider.BalanceResult> balance = client.getBalance("1eefc4f453539e5ee732b49eb4792b268c2f3908");
        System.out.println(new Gson().toJson(balance));

This is the JAVA version of how to get ballance from address.
My question is where you are getting that class HttpProvider from?
If you are not taking it from any standart lib. and you are writing it what should be there implemented?