@Override
    public Class<?> getColumnClass(int columnIndex) {
        if (columnIndex == DELIVERY_PACKET_ID) {
            return Integer.class;
        } else if (columnIndex == MEMBER_NAME) {
            return String.class;
        } else if (columnIndex == EVENT) {
            return String.class;
        } else if (columnIndex == DELIVERY_DATE) {
            return Date.class;
        } else if (columnIndex == EXPECTED_RETURN_DATE) {
            return Date.class;
        } else {
            return Object.class;
        }
    }