code: public void setInterval(String interval) {
  	if (StringUtil.isEmpty(interval)) return;
  	interval = interval.trim().toLowerCase();
  	if (interval.equals("week")) this.interval = "weekly";
  	else if (interval.equals("day")) this.interval = "daily";
  	else if (interval.equals("month")) this.interval = "monthly";
  	else if (interval.equals("year")) this.interval = "yearly";
  	this.interval = interval;
      }
docs: set the value interval Required when creating tasks with action = 'update'. Interval at which
  task should be scheduled. Can be set in seconds or as Once, Daily, Weekly, and Monthly. The
  default interval is one hour. The minimum interval is one minute.
  
  @param interval value to set