[XmlElement(ElementName = "PARENTNAME")]
public string PARENTNAME { get; set; }  //This is perfect mapped
[XmlElement(ElementName = "DISPLAYCONTACT.CONTACTNAME")]
public string DISPLAYCONTACTCONTACTNAME { get; set; } // This is not mapped
[XmlElement(ElementName = "DISPLAYCONTACT.COMPANYNAME")]
public string DISPLAYCONTACTCOMPANYNAME { get; set; }

XmlDocument doc = new XmlDocument();
        doc.LoadXml(custome‌​rString);
        StringWriter sw = new StringWriter();
        XmlTextWriter xw = new XmlTextWriter(sw);
        doc.WriteTo(xw);
        String XmlString = sw.ToString();
        string xmlToJson = JsonConvert.SerializeXmlNode(doc);
        var deserialized = JsonConvert.SerializeXmlNode(doc);
        var custome‌​r = new CusGetResIn();
        custome‌​r= JsonConvert.DeserializeObject<CusGetResIn>(deserialized);