Inheritance: HqlStatement
		public void AddGroupByClause(HqlGroupBy groupBy)
		{
			_root.As<HqlQuery>().AddChild(groupBy);
		}
		public void AddGroupByClause(HqlGroupBy groupBy)
		{
			this._root.AddChild(groupBy);
		}
		private void ProcessGroupByOperator(GroupResultOperator resultOperator)
		{
			var visitor = new HqlGeneratorExpressionTreeVisitor(_parameterAggregator);
			visitor.Visit(resultOperator.KeySelector);
			_groupByClause = _hqlTreeBuilder.GroupBy();
			_groupByClause.AddChild(visitor.GetHqlTreeNodes().Single());
		}