/// <summary>
        /// Return dynamic cells of the group header.
        /// </summary>
        public void GroupHeaderCells(Action<HeaderCellsBuilder> headerCellsBuilder)
        {
            Func<IList<CellData>, IList<SummaryCellData>, List<CellAttributes>> func = (rowdata, summaryData) =>
            {
                var builder = new HeaderCellsBuilder { RowData = rowdata, SummaryData = summaryData };
                headerCellsBuilder(builder);
                return builder.HeaderCells;
            };

            _defaultHeaderProvider.GroupHeaderCells = func;
        }
        /// <summary>
        /// Return dynamic cells of the group header.
        /// </summary>
        public void GroupHeaderCells(Action <HeaderCellsBuilder> headerCellsBuilder)
        {
            Func <IList <CellData>, IList <SummaryCellData>, List <CellAttributes> > func = (rowdata, summaryData) =>
            {
                var builder = new HeaderCellsBuilder {
                    RowData = rowdata, SummaryData = summaryData
                };
                headerCellsBuilder(builder);
                return(builder.HeaderCells);
            };

            _defaultHeaderProvider.GroupHeaderCells = func;
        }