Open the /ViewModels/TokenResponseViewModel.cs file and update it in the following way:

[...]

#region Properties
public string token { get; set; }
public int expiration { get; set; }
public string refresh_token { get; set; }
#endregion

[...]

This property will be used by our TokenController to send the refresh token to the client --along with the access token--upon a successful login.