code: public static void initializeClient(Config config, String sessionToken) {
          // Override returnUrl until introduction of FilestackUi class which will allow to set this
          // all up manually.
          Config overridenConfig = new Config(config.getApiKey(), "filestack://done",
                  config.getPolicy(), config.getSignature());
  
          client = new Client(overridenConfig);
          client.setSessionToken(sessionToken);
      }
docs: Create the Java SDK client and set a session token. The token maintains cloud auth state.