columnNames property
The collection of string which is the GridColumn.columnName of the columns defined in the SfDataGrid.
The columns are spanned as a stacked header based on this collection. If the given collection has the sequence of columns which are presented in the SfDataGrid, those columns will be spanned. Otherwise, stacked header is added for each column which are not in sequence order in regular columns.
Implementation
final List<String> columnNames;