如何使用fl_chart showingTooltipIndicators？

import 'package:flutter/material.dart';
import 'package:fl_chart/fl_chart.dart';

class MyChartPage extends StatelessWidget {
  final List<ChartData> data = [
    ChartData(x: "Jan", y: 30),
    ChartData(x: "Feb", y: 50),
    ChartData(x: "Mar", y: 80),
    ChartData(x: "Apr", y: 60),
    ChartData(x: "May", y: 90),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("My Chart"),
      ),
      body: Column(
        children: [
          Text(
            "Chart Title",
            style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
          ),
          Container(
            height: 300,
            child: BarChart(
              BarChartData(
                barGroups: data
                    .map((item) =>
                        BarChartGroupData(x: item.x, barRods: [
                          BarChartRodData(y: item.y.toDouble(), colors: [Colors.blue])
                        ]))
                    .toList(),
              ),
              showingTooltipIndicators: [0, 1, 2, 3, 4], // 控制显示提示信息的数据点索引
            ),
          ),
        ],
      ),
    );
  }
}

class ChartData {
  final String x;
  final int y;

  ChartData({required this.x, required this.y});
}