TimerEntity#getPersistentState() should include duedate field

Similar to MessageEntity, TimerEntity should also contains this method override:

  public Object getPersistentState() {
    Map<String, Object> persistentState = (Map<String, Object>) super.getPersistentState();
    persistentState.put("duedate", getDuedate());
    return persistentState;
  }

The sql 'updateTimer' in Job.xml already includes the duedate, it's just part of the persistentState map in the code.

I need to programmatically change the duedate and even though I can modify the duedate on the TimerEntity, the change does not trigger a flush to the DB with the new value.