@Override
    public Class<?> getColumnClass(int columnIndex) {
        if (columnIndex == NUMBER) {
            return Integer.class;
        } else if (columnIndex == TYPE) {
            return String.class;
        } else if (columnIndex == MODEL) {
            return String.class;
        } else if (columnIndex == RETURN_DATE) {
            return Date.class;
        } else {
            return Object.class;
        }
    }