code: @Override
    public Calendar retrieveCalendar(String calName) {
  
      synchronized (lock) {
        Calendar cal = calendarsByName.get(calName);
        if (cal != null) {
          return (Calendar) cal.clone();
        }
        return null;
      }
    }
docs: Retrieve the given <code>{@link org.quartz.triggers.Trigger}</code>.
  
  @param calName The name of the <code>Calendar</code> to be retrieved.
  @return The desired <code>Calendar</code>, or null if there is no match.