Example of Disposing a Class Level object in StartUp using IHostApplicationLifetime

Startup.cs

public class StartUp
{
    private readonly SomeDisposable _someDisposable;

    public StartUp()
    {
        _someDisposable = new SomeDisposable();
    }
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddSingleton<ISomeDisposable>(_someDisposable);
    }

    public void Configure(IApplicationBuilder app, IHostApplicationLifetime applicationLifetime)
    {
        applicationLifetime.ApplicationStopping.Register(() => { _someDisposable.Dispose(); });
    }
}