Can't validate event notification endpoint URL

[freelancer.nak (Naeem Ahmed)]

@sales4 @sfaraclas @littlelaureates Here is C# working code

    [HttpPost(Name = "events")]
    public ActionResult Events(ValidateUrlEvent notification)
    {
        var encoding = new System.Text.ASCIIEncoding();

        var sha256 = new System.Security.Cryptography.HMACSHA256();
        sha256.Key = encoding.GetBytes("Your Event Secret Token");

        var hash = sha256.ComputeHash(encoding.GetBytes(notification.payload.plainToken));

        var hashed=ToHex(hash,false);

        return Ok(
            new
            {
                plainToken = notification.payload.plainToken,
                encryptedToken = hashed
            }
        );
    }

    private static string ToHex(byte[] bytes, bool upperCase)
    {
        StringBuilder result = new StringBuilder(bytes.Length * 2);
        for (int i = 0; i < bytes.Length; i++)
            result.Append(bytes[i].ToString(upperCase ? "X2" : "x2"));
        return result.ToString();
    }