如何在flutter中清除PaginatedDataTable的DataTableSource？

import 'package:flutter/material.dart';

class CustomDataTableSource extends DataTableSource {
  // 实现DataTableSource的必要方法

  @override
  int get rowCount => 10;

  @override
  bool get isRowCountApproximate => false;

  @override
  int get selectedRowCount => 0;

  @override
  DataRow getRow(int index) {
    // 返回每一行的数据
    return DataRow.byIndex(
      index: index,
      cells: [
        DataCell(Text('Cell $index')),
        DataCell(Text('Cell $index')),
        DataCell(Text('Cell $index')),
      ],
    );
  }
}

class MyDataTable extends StatefulWidget {
  @override
  _MyDataTableState createState() => _MyDataTableState();
}

class _MyDataTableState extends State<MyDataTable> {
  CustomDataTableSource _data = CustomDataTableSource();

  void clearDataTableSource() {
    setState(() {
      _data = CustomDataTableSource();
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('PaginatedDataTable Example'),
      ),
      body: Column(
        children: [
          RaisedButton(
            child: Text('Clear DataTable Source'),
            onPressed: clearDataTableSource,
          ),
          Expanded(
            child: PaginatedDataTable(
              header: Text('DataTable'),
              source: _data,
              columns: [
                DataColumn(label: Text('Column 1')),
                DataColumn(label: Text('Column 2')),
                DataColumn(label: Text('Column 3')),
              ],
              rowsPerPage: 5,
            ),
          ),
        ],
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyDataTable(),
  ));
}