FindItemsWithFolderIdAndViewAndGrouping method 
    
    
  
Obtains a grouped list of items by searching the contents of a specific folder. Calling this method results in a call to EWS.
The Id of the folder in which to search for items.
The view controlling the number of items returned.
The group by clause.
    
  Implementation
  Future<GroupedFindItemsResults<Item>?>
    FindItemsWithFolderIdAndViewAndGrouping(
        FolderId parentFolderId, ViewBase view, Grouping groupBy) async {
  EwsUtilities.ValidateParam(groupBy, "groupBy");
  ServiceResponseCollection<FindItemResponse<Item>> responses =
      await this.FindItemsGeneric<Item>(
          [parentFolderId],
          null,
          /* searchFilter */
          null,
          /* queryString */
          view,
          groupBy,
          ServiceErrorHandling.ThrowOnError);
  return responses[0].GroupedFindResults;
}