如何在ExpansionPanelList中添加报头之间的间距？

ExpansionPanelList(
  children: [
    ExpansionPanel(
      headerBuilder: (context, isExpanded) {
        return ListTile(
          title: Text('Panel 1'),
        );
      },
      body: Container(
        child: Text('Content 1'),
      ),
      isExpanded: false,
    ),
    ExpansionPanel(
      headerBuilder: (context, isExpanded) {
        return ListTile(
          title: Text('Panel 2'),
        );
      },
      body: Container(
        child: Text('Content 2'),
      ),
      isExpanded: false,
    ),
  ],
  expansionCallback: (panelIndex, isExpanded) {
    // 点击展开/收起面板的回调函数
  },
  // 自定义ExpansionPanelHeader的样式
  expansionHeaderStyle: Theme.of(context).textTheme.subtitle1.copyWith(
    // 设置报头之间的间距
    padding: EdgeInsets.symmetric(vertical: 8.0),
  ),
)