code: @Nullable
    public static XMLGregorianCalendar getXMLCalendarDate (@Nullable final LocalDate aBase)
    {
      if (aBase == null)
        return null;
      return s_aDTFactory.newXMLGregorianCalendarDate (aBase.getYear (),
                                                       aBase.getMonth ().getValue (),
                                                       aBase.getDayOfMonth (),
                                                       DatatypeConstants.FIELD_UNDEFINED);
    }
docs: Get the passed object as {@link XMLGregorianCalendar} date (without a
  time).
  
  @param aBase
  The source object. May be <code>null</code>.
  @return <code>null</code> if the parameter is <code>null</code>.