OfficeOpenXml.Table.PivotTable.ExcelPivotTableField.ValidateGrouping C# (CSharp) Method

        private void ValidateGrouping()
        {
            if (!(IsColumnField || IsRowField))
            {
                throw (new Exception("Field must be a row or column field"));
            }
            foreach (var field in _table.Fields)
            {
                if (field.Grouping != null)
                {
                    throw (new Exception("Grouping already exists"));
                }
            }
        }