GenerateToken.cs

public JwtSecurityToken Generate(string userId, IEnumerable<Claim> claims)
{
    Requires.NotEmpty(userId, nameof(userId));

    // We're using a DateTimeOffset and later using the DateTime property thereof so we don't
    // have to mess with extension methods to grab UNIX time, as DateTimeOffset has those built in.
    var timeStamp = DateTimeOffset.UtcNow;

    var token = new JwtSecurityToken(_options.Issuer, _options.Audience, claims, timeStamp.DateTime,
        timeStamp.Add(_options.Expiration).DateTime, _options.SigningCredentials);

    return token;
}