Kendo grid server-side grouping, return value property "Items" instead of "items" cause exception in kendo.all.js

[Claudio]

Hi, my KendoUI version is v2015.2.902, i use a kendo grid for server paging, sorting, filtering and now i would like to add grouping functionality.
I use "function read" mode for dataSource calling asp.net mvc controller method. (server side request object is a Kendo.Mvc.UI.DataSourceRequest object)
this is my dataSource configuration:

let dataSource: any = {
  batch: true,
  serverPaging: true,
  serverSorting: true,
  serverFiltering: true,
  serverGrouping: true,
  page: 1,
  pageSize: 20,
  transport:
  {
      read: function (options)
      {
          kendo.data.transports["aspnetmvc-ajax"].fn.options.options = { prefix: '' };
          let request = kendo.data.transports["aspnetmvc-ajax"].fn.options.parameterMap(options.data, "read", false);

          thisObject.httpService.GetNodes(request)
          .then(function (args: IHttpServiceParameters)
          {
              options.success(args.data);
          });
      }
  },
  schema:
  {
      data: function (data)
      {
          return data.Data;
      },
      total: function (data)
      {
          return data.Total;
      },
      groups: function (data)
      {
          return data.Data;
      },
      model: model
  }
};

if i not use grouping all work fine, but using grouping the data result object seem not binding correctly.

args.data.Data returned from server has this schema:

[{ AggregateFunctionsProjection: null, 
   Aggregates: {}, 
   HasSubGroups: false, 
   Items: [],      <--- Keep note of this element name
   Key: "Invoice", 
   Member: "InvoiceColumnName", 
   Subgroups: [], 
   value: undefined 
 }, 
...]

the problem is when kendo.all.js parse the response of the server, passed from args.data.Data to convertGroup function (kendo.all.js line 7049)
in this function there is a call who reference to record.items object but the object in data returned from server is called Items (starting with uppercase)

kendo.all.js code:
function convertGroup(data, getters, modelInstance, originalFieldNames, fieldNames) {
      var record,
          idx,
          fieldName,
          length;

      for (idx = 0, length = data.length; idx < length; idx++) {
          record = data[idx];

          fieldName = originalFieldNames[record.field];
          if (fieldName && fieldName != record.field) {
              record.field = fieldName;
          }

          record.value = modelInstance._parse(record.field, record.value);

          if (record.hasSubgroups) {
              convertGroup(record.items, getters, modelInstance, originalFieldNames, fieldNames);    <--- Here the problem !!
          } else {
              convertRecords(record.items, getters, modelInstance, originalFieldNames, fieldNames);  <--- Here the problem !!
          }
      }
  }

do you have any suggestion? why the object returned from server have Items property insted of items?
How to solve?
In attachment the google developer tools screenshot.

Thanks

[Rosen]

Hello Claudio,

Indeed, the data returned by the DataSourceResult will not exactly match the data expected by the DataSource. This is handled by the aspnetmvc-ajax schema implementation as it is designed to work with the DataSourceResult data. Thus, you should use the aspnetmvc-ajax schema group and aggregates (if needed) function or convert the data on your own.

schema:
{
    data: function (data)
    {
        return data.Data;
    },
    total: function (data)
    {
        return data.Total;
    },
    groups: kendo.data.schemas["aspnetmvc-ajax"].groups,
    model: model
}

Regards,
Rosen
Telerik