RPS.Config.jsGetFilterColumns C# (CSharp) Method

        public string jsGetFilterColumns()
        {
            Dictionary<string, ColumnInfo> columns;
            columns = Constants.FileNodesDefinition.columns.Union(Constants.MetadataDefinition.columns)
                .ToLookup(pair => pair.Key, pair => pair.Value)
                .ToDictionary(group => group.Key, group => group.First());
            return JsonConvert.SerializeObject(columns/*, Newtonsoft.Json.Formatting.Indented*/);
        }