表格无法导出分组表头

`this.$refs.tableExcel.exportCsv({
filename: this.excelTitle,
original: false,
columns: this.tableColumns.filter(function(col, index) {
let childs = col.children
if (childs) {
childs.forEach(element => {
element.title = col.title + element.title
})
return childs
} else {
return col
}
})
})`
我用了这个办法，把一级表头的名字和二级表头拼接在一起，请问这样的方式合适么

Start from the `this.$refs.tableExcel.exportCsv` call and the `tableColumns` data shown in the issue. Check how grouped columns are handled during CSV export, then verify that exported headers preserve the intended first- and second-level names without mutating the table column definitions.

Written by the indexing model from the issue text.