private bool setColumnAggregateFunc(string columnName, ColumnAttributes colDef)
{
if (_conventions == null || _conventions.ColumnNamesAggregateFunctions == null) return false;
var func = _conventions.ColumnNamesAggregateFunctions.FirstOrDefault(x => x.Key == columnName);
if (func.Value == null) return false;
colDef.AggregateFunction = func.Value;
return true;
}