How to validate offline license file with the NetLicensing C# library

[r-brown]

Question
How to validate offline license file with the NetLicensing C# library?
I'm getting the exception when I called Validateofflinmethod

Additional Context

[r-brown]

In order to use Offline validation using License File publicKey need to be set in the validation contect.

Please find below sample code for C# library:

using System;
using NetLicensingClient.Entities;

namespace NetLicensingClient
{
    class NetLicensingClient_demo
    {
        static int Main(string[] args)
        {
                string publicKey = @"-----BEGIN PUBLIC KEY-----
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAu5grobcnjPhzOvyG05DO
OW6SlUIKa7omhJLIXl8D8fohuHUaZLoGA2Fot4OP/qFSg0DK4egbCbU+pDrasMvK
vNTCMzw0ypzbyBEaYSm6wtEeU45ppawj0HjOh3NRp2Ds0hR8xSMKFRc/4d87hskj
yjKXOqoOZhqjXwYk7ocIe6ADPpF4YCs5eY4/3CL1JnItdlKQRsl8ZJ0Yqe+figf9
agCWvQ0O0faRdmgmr7eUhU9aXNvSJaVJXbg6TjhhxVujzehF8sh/7sxgGwqbyunE
15OWo6dArRCyNUeROu+9Jp4tET+2RA/PuqQbWW6EbJWBhpkqNdzi9CYuhuUjvk8m
dwIDAQAB
-----END PUBLIC KEY-----";

                Context offlineContext = new Context();
                offlineContext.publicKey = publicKey;

                string validationFile = @"<?xml version=""1.0"" encoding=""UTF-8"" standalone=""yes""?><ns2:netlicensing xmlns=""http://www.w3.org/2000/09/xmldsig#"" xmlns:ns2=""http://netlicensing.labs64.com/schema/context"" ttl=""2020-12-28T22:53:06.681Z""><Signature><SignedInfo><CanonicalizationMethod Algorithm=""http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments""/><SignatureMethod Algorithm=""http://www.w3.org/2000/09/xmldsig#rsa-sha1""/><Reference URI=""""><Transforms><Transform Algorithm=""http://www.w3.org/2000/09/xmldsig#enveloped-signature""/></Transforms><DigestMethod Algorithm=""http://www.w3.org/2000/09/xmldsig#sha1""/><DigestValue>ICC1F7ZKeQoayrzn1iGtw7Zt96s=</DigestValue></Reference></SignedInfo><SignatureValue>jYb0aGBPR9Rn4HVRJhBsIRafzW1k3D/GF7GZ62nT8dwvJszGB0kEXdFrXTj7FhUeiBcBlqxcsEUUKA5XbE7LGbNm+V+f5xZu/+n/d/miufKPAIk6CN5xoZQLDRGRSruW0LiKJsnkbzHvIF4u6G/HUyQpUfrxwiqXb+tYFpiaMgcSHL5xGzRq5Mqusw21Cdq81MhUb9oUoujgisIZWqNyebOqWuzOjNJOy0y2uml4I5U5tBAL1OlrQKjfPUiy369HwMl37A7dR9oVcahb6/YPI039xeLTn+WzyFPIV7f41o6Ytq4Iefl6swj/elNKTHi9bYzcnjmM7ebOd+hinm8feA==</SignatureValue></Signature><ns2:infos/><ns2:items><ns2:item type=""ProductModuleValidation""><ns2:property name=""productModuleNumber"">Msb-DEMO</ns2:property><ns2:property name=""valid"">true</ns2:property><ns2:property name=""expires"">2021-04-21T20:15:45.694Z</ns2:property><ns2:property name=""productModuleName"">Module using ""Subscription"" licensing model</ns2:property><ns2:property name=""licensingModel"">Subscription</ns2:property></ns2:item></ns2:items></ns2:netlicensing>";

                Console.WriteLine("Offline validation file: {0}", validationFile);

                ValidationResult validationOfflineResult = ValidationService.validateOffline(offlineContext, validationFile);
                ConsoleWriter.WriteEntity("Offline validation result:", validationOfflineResult);

                return 0;
        }
    }
}