How to check if a type implements a an interface with generic type?

I have the following two interfaces.

public interface IRegisterToContainer
{
}

public interface IRegisterPerRequest<T> : IRegisterToContainer
{
}

public interface IRegisterPerRequest : IRegisterToContainer
{
}

The two interfaces will be used by the application bootstrapper to register classes into the IoC controller using reflection.

I basically want to take any class that implements these interfaces and register it to the container.

This is how I am trying to use reflection to register these types

var types = AppDomain.CurrentDomain.GetAssemblies()
                                   .Where(assembly => assembly.IsDynamic == false)

.SelectMany(assembly => assembly.GetTypes()) .Where(x => x.IsClass && !x.IsInterface) .ToList();

    foreach (Type type in types)
    {
        // Here I am trying to find any type that is assignable from the IRegisterPerRequest<> interface
        if (type.IsGenericType && typeof(IRegisterPerRequest<>).IsAssignableFrom(type))
        {
            container.RegisterType(type.GetGenericArguments()[0], type, type.FullName, new PerRequestLifetimeManager());
        }
        // Here if the type implements the IRegisterPerRequest, I want to register it
        else if (typeof(IRegisterPerRequest).IsAssignableFrom(type))
        {
            container.RegisterType(typeof(IRegisterPerRequest), type, type.FullName, new PerRequestLifetimeManager());
        }
    }

But for some reason, the first conditions is not being detected. Here is an use-case example

public interface ICarService
{
    public Car GetCarByShape(sting shape);
}

public class CarService ICarService, IRegisterPerRequest<ICarService>
{
    protected ICarRepository CarContext;

    public CarService(ICarRepository car)
    {
        CarContext = car;
    }

    public Car GetCarByShape(sting shape)
    {
        return CarContext.Find(x => x.Shape == shape)
                         .FirstOrDefault();
    }
}

I am basically trying to tell unity, register the type ICarService to CarService at run time.

How can I correctly use reflection to check of the given type implements the IRegisterPerRequest<T> interface?