code: public void checkForUpdate(UpdateCheckListener updateCheckListener) {
          listeners.add(updateCheckListener);
          if (scheduler != null) {
              scheduler.schedule(new UpdateCheckTask(this, versionServiceUrl, productName), 0, SECONDS);
          } else {
              // the scheduler won't be provided if the service isn't actually running,
              // but management may still ask for a check on update
              new UpdateCheckTask(this, versionServiceUrl, productName).run();
          }
      }
docs: Forces a check for an update and registers the listener if it is not already registered
  @param updateCheckListener