My grid bind to ExpandoObjects, and I would like to implement a Group Header.

So I referenced these two documents
https://docs.telerik.com/blazor-ui/knowledge-base/grid-binding-to-expando-object

https://docs.telerik.com/blazor-ui/components/grid/columns/multi-column-headers

From the first document, it make sense to me that we need to set FieldType for each column that binds to ExpandoObject, but it seems this restriction also applies to the group header column, which does not make sense.

Foe example:

<TelerikGrid Data="@GridData"
             Pageable="true"
             Sortable="true"
             FilterMode="@GridFilterMode.FilterRow">
    <GridColumns>
        <GridColumn Title="Test Group Header">
            <Columns>
                <GridColumn Field="PropertyInt" Title="Int Column" FieldType="@typeof(int)" />
                <GridColumn Field="PropertyString" Title="String Column" FieldType="@typeof(string)" />
                <GridColumn Field="PropertyDate" Title="DateTime Column" FieldType="@typeof(DateTime)" />
            </Columns>
        </GridColumn>
    </GridColumns>
</TelerikGrid>

I get error:

I need to set FieldType on the "Test Group Header" column to an arbitrary value to get rid of this error.