Creating a Group with a List of Elements

Project.Current.GetItems<LayoutProjectItem>().FirstOrDefault()?.GetLayout();
            
            List<Element> elements = new List<Element>();
            for (int i = 0; i < 100; i++)
            {
                List<Coordinate2D> lineCoordinates = new List<Coordinate2D> { new Coordinate2D { X = i, Y = 0 }, new Coordinate2D { X = i, Y = 100 } };
                Polyline polylineTic = PolylineBuilder.CreatePolyline(lineCoordinates);
                CIMLineSymbol lineSym = SymbolFactory.Instance.ConstructLineSymbol(ColorFactory.Instance.BlackRGB, 1.0, SimpleLineStyle.Solid);
                GraphicElement lineElm = LayoutElementFactory.Instance.CreateLineGraphicElement(layout, polylineTic, lineSym);
                CIMElement cimElement = lineElm.GetDefinition();
                cimElement.Name = "Line" + i;
                lineElm.SetDefinition(cimElement);
                elements.Add(lineElm);
            }

            GroupElement groupElement = LayoutElementFactory.Instance.CreateGroupElement(layout, elements);
            CIMElement cimGroupElement = groupElement.GetDefinition();
            cimGroupElement.Name = "First Level Group";
            groupElement.SetDefinition(cimGroupElement);