code: protected static Date getTime(final Date referenceDate, final Calendar cal) {
          final Date zonedDate = new DateTime(referenceDate);
          zonedDate.setTime(cal.getTime().getTime());
          return zonedDate;
      }
docs: Get a DateTime from cal.getTime() with the timezone of the given reference date.
  
  @param referenceDate
  @param cal
  @return