Why should I use GroupInfoCollection for DataGrid grouping?

[djonasdev]

You use the GroupInfoCollection class both in your source code (of example application;

WindowsCommunityToolkit/Microsoft.Toolkit.Uwp.SampleApp/Data/DataGridDataSource.cs

Line 167 in b21dbe7

public CollectionViewSource GroupData()

) and in the official MS documentation (https://docs.microsoft.com/de-de/windows/communitytoolkit/controls/datagrid_guidance/group_sort_filter).

Grouping works just as well with an ObservableCollection. However, my question here is how do I get the GroupInfoCollection.Key in the DataGrid_OnLoadingRowGroup eventHandler or what was the Key property intended for?