protected void addTrigger(
        SchedulerEntry schedulerEntry, ServiceReference<SchedulerEntry> serviceReference) {

      String propertyKey = schedulerEntry.getPropertyKey();

      if (Validator.isNull(propertyKey)) {
        return;
      }

      long bundleId = GetterUtil.getLong(serviceReference.getProperty("bundle.id"), -1);

      String triggerValue = null;

      if (bundleId != 0) {
        Class<?> clazz = schedulerEntry.getClass();

        ClassLoader classloader = clazz.getClassLoader();

        triggerValue = getPluginPropertyValue(classloader, propertyKey);
      } else {
        triggerValue = PrefsPropsUtil.getString(propertyKey);
      }

      if (_log.isDebugEnabled()) {
        _log.debug("Scheduler property key " + propertyKey + " has trigger value " + triggerValue);
      }

      if (Validator.isNotNull(triggerValue)) {
        schedulerEntry.setTriggerValue(triggerValue);
      }
    }
  private void _start() {
    if (_log.isDebugEnabled()) {
      _log.debug("Start");
    }

    try {
      SchedulerEntry schedulerEntry = new SchedulerEntryImpl();

      schedulerEntry.setEventListenerClass(POPNotificationsMessageListener.class.getName());
      schedulerEntry.setTimeUnit(TimeUnit.MINUTE);
      schedulerEntry.setTriggerType(TriggerType.SIMPLE);
      schedulerEntry.setTriggerValue(PropsValues.POP_SERVER_NOTIFICATIONS_INTERVAL);

      SchedulerEngineUtil.schedule(
          schedulerEntry, StorageType.MEMORY_CLUSTERED, PortalClassLoaderUtil.getClassLoader(), 0);
    } catch (Exception e) {
      _log.error(e, e);
    }
  }