The NHibernate.Web.Example "project" in the NHibernate.Everything.sln is problematic in how old it is. It is an ASP.Net Web Site; it doesn't even have a project file but the definition is embedded in the .sln; it requires manually switching to Classic pipeline mode instead of the default Integrated; and finally it has no path forward into .Net Core.
While it does have an example of implementing an IHttpModule for the Classic pipeline mode for session lifetime control, that's not really the operative way to do it with dependency injection available.
The entire project should be replaced with an ASP.NET Core Web Application using Razor Pages and targeting the .NET Framework.
This is probably a dependency of NH-3807.