code: private GregorianCalendar getLastReleventDate(GregorianCalendar currentDate) {
  		int age=this.getProperties().getMaxFileAge();
  		GregorianCalendar result=new GregorianCalendar(currentDate.get(Calendar.YEAR),currentDate.get(Calendar.MONTH),currentDate.get(Calendar.DAY_OF_MONTH));
  		result.add(Calendar.DAY_OF_MONTH, -age);
  		return result;
  	}
docs: Get the last date to keep logs from, by a given current date.
  @param currentDate the date of today
  @return the last date to keep log files from.