Add polygon to DTO convert strategy

StructureHelperCommon/Models/Shapes/PolygonLineSegment.cs

@@ -0,0 +1,22 @@
+using System;
+
+namespace StructureHelperCommon.Models.Shapes
+{
+    public class PolygonLineSegment : IPolygonLineSegment
+    {
+        public Guid Id { get; }
+        public IVertex StartVertex { get; }
+        public IVertex EndVertex { get; }
+
+
+        public PolygonLineSegment(Guid id)
+        {
+            Id = id;
+        }
+
+        public void UpdateEndFromParameters()
+        {
+            //nothing to do
+        }
+    }
+}