code: public static DateTime toDateSimple(String str, short convertingType, boolean alsoMonthString, TimeZone timeZone) throws PageException {
  	DateTime dt = toDateSimple(str, convertingType, alsoMonthString, timeZone, null);
  	if (dt == null) throw new ExpressionException("can't cast value to a Date Object");
  	return dt;
      }
docs: converts a Object to a DateTime Object, returns null if invalid string
  
  @param str Stringt to Convert
  @param convertingType one of the following values: - CONVERTING_TYPE_NONE: number are not
  converted at all - CONVERTING_TYPE_YEAR: integers are handled as years -
  CONVERTING_TYPE_OFFSET: numbers are handled as offset from 1899-12-30 00:00:00 UTC
  @param timeZone
  @return coverted Date Time Object
  @throws PageException