code: public static void initialize(String applicationId, String clientKey, String masterKey) {
      AVOSCloud.setLogLevel(AVLogger.Level.ALL);// let log4j make decision.
      AppConfiguration.setLogAdapter(new Log4jAdapter());
      AVOSCloud.initialize(applicationId, clientKey);
  
      appConf = EngineAppConfiguration.instance(applicationId, clientKey, masterKey);
      appRouter = new EnvFirstAppRouter();
      appRouter.fetchServerHostsInBackground(applicationId).blockingSingle();
    }
docs: <p>
  Authenticates this client as belonging to your application. This must be called before your
  application can use the AVOSCloud library. The recommended way is to put a call to
  LeanEngine.initialize in each of your onCreate methods.
  </p>
  
  @param applicationId The application id provided in the AVOSCloud dashboard.
  @param clientKey The client key provided in the AVOSCloud dashboard.
  @param masterKey The master key provided in the AVOSCloud dashboard.