using System;

using System.Linq;

using System.Reflection;

using System.Xml;

using System.IdentityModel.Tokens;

using System.Threading.Tasks;

using System.Collections.Generic;

using System.IdentityModel.Policy;

​

public class Program

{

    public static async Task Main()

    {

        var doc = new System.Xml.XmlDocument();

        doc.LoadXml("<root />");

        GenericXmlSecurityToken token = new GenericXmlSecurityToken(doc.DocumentElement, null, DateTime.Now, DateTime.Now.AddDays(1), null, null, new List<IAuthorizationPolicy>().AsReadOnly());

        var tokenXmlProp = typeof(GenericXmlSecurityToken).GetProperties(BindingFlags.Public | BindingFlags.Instance | BindingFlags.DeclaredOnly).Single(p => p.Name == "TokenXml");

        var tokenXml = (XmlElement)tokenXmlProp.GetValue(token);

        Console.WriteLine(tokenXml); // Works

        Console.WriteLine(tokenXml.OuterXml); // Contains expected contained value, "<root />"

        //Console.WriteLine(token.TokenXml); // Does not compile, no definition for "TokenXml"

    }

}