public IReadOnlyList<Element> GetElementsAsFlattenedList()

//on the QueuedTask
//Find elements by name
var layoutElementsToFind = layout.FindElements(new List<string>() { "Point 1", "Line 3", "Text 1" });
//Get the collection of elements from the page layout. Nesting within GroupElement is preserved.
var elementCollection = layout.GetElements();
//Get the collection of Element from the page layout as a flattened list. Nested groups within GroupElement are not preserved.
var elements = layout.GetElementsAsFlattenedList();
//Convert collection of the elements to a collection of GraphicElements.
var graphicElements = elements.ToList().ConvertAll(x => (GraphicElement)x);
//Find elements by type
//Find all point graphics in the Layout
var pointGraphics = graphicElements.Where(elem => elem.GetGraphic() is CIMPointGraphic);
//Find all line graphics in the Graphics Layer
var lineGraphics = graphicElements.Where(elem => elem.GetGraphic() is CIMLineGraphic);
////Find all polygon graphics in the Graphics Layer
var polyGraphics = graphicElements.Where(elem => elem.GetGraphic() is CIMPolygonGraphic);
////Find all text graphics in the Graphics Layer
var textGraphics = graphicElements.Where(elem => elem.GetGraphic() is CIMTextGraphic);
////Find all picture graphics in the Graphics Layer
var pictureGraphic = graphicElements.Where(elem => elem.GetGraphic() is CIMPictureGraphic);