code: @Override
      public void write( final DateTime obj, final javolution.xml.XMLFormat.OutputElement output ) throws XMLStreamException {
          output.setAttribute( MILLIS, obj.getMillis() );
          final String chronologyId = getChronologyId( obj.getChronology() );
          if ( chronologyId != null ) {
              output.setAttribute( CHRONOLOGY, chronologyId );
          }
          if ( obj.getZone() != null && obj.getZone() != DateTimeZone.getDefault() ) {
              output.setAttribute( TIME_ZONE, obj.getZone().getID() );
          }
      }
docs: {@inheritDoc}