private List <Converter.XmlVertex> createXmlVertices(List <Geometry.Segment2D> graphSegments)
        {
            List <Converter.XmlVertex> xmlVertices = new List <Converter.XmlVertex>();

            foreach (Segment2D currentSegment in graphSegments)
            {
                Vector2D segmentsStart = currentSegment.getVertices()[0];
                Vector2D segmentsEnd   = currentSegment.getVertices()[1];

                if (this.getEqualXmlVertex(xmlVertices, segmentsStart) == null)
                {
                    xmlVertices.Add(xmlFactory.createXmlVertex(null, segmentsStart));
                }
                if (this.getEqualXmlVertex(xmlVertices, segmentsEnd) == null)
                {
                    xmlVertices.Add(xmlFactory.createXmlVertex(null, segmentsEnd));
                }
            }

            return(xmlVertices);
        }