code: public ProjectCalendar addResourceCalendar() throws MPXJException
     {
        if (getResourceCalendar() != null)
        {
           throw new MPXJException(MPXJException.MAXIMUM_RECORDS);
        }
  
        ProjectCalendar calendar = new ProjectCalendar(getParentFile());
        setResourceCalendar(calendar);
        return calendar;
     }
docs: This method allows a resource calendar to be added to a resource.
  
  @return ResourceCalendar
  @throws MPXJException if more than one calendar is added