How to pass a RequestDelegate to a MiddleWare Constructor? - asp.net-core-6.0

Question

I'm reading a chapter in Apress ASP.Net Core 6 and it has a lot of examples of middleware.
There is a pattern in middleware where you can have the middleware class act as terminal or non-terminal.
A private nullable RequestDelegate field is declared. Then one constructor takes a RequestDelegate and one constructor takes no parameters so the RequestDelegate field will be null.
If the RequestDelgate is not null, the middleware calls the next middleware in the pipeline. Otherwise the pipeline terminates.
Here is one example:
namespace Platform
{
public class Capital
{
private RequestDelegate? next;
public Capital() { }
public Capital(RequestDelegate nextDelegate)
{
next = nextDelegate;
}
public async Task Invoke(HttpContext context)
{
string[] parts = context.Request.Path.ToString()
.Split("/", StringSplitOptions.RemoveEmptyEntries);
if (parts.Length == 2 && parts[0] == "capital")
{
string? capital = null;
string country = parts[1];
switch (country.ToLower())
{
case "uk":
capital = "London";
break;
case "france":
capital = "Paris";
break;
case "monoco":
context.Response.Redirect($"/population/{country}");
return;
}
if (capital != null)
{
await context.Response
.WriteAsync($"{capital} is the capital of {country}");
return;
}
}
if (next != null)
{
await next(context);
}
}
}
}
Then here is the call in program.cs:
using Platform;
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
app.UseMiddleware<Population>();
app.UseMiddleware<Capital>();
app.Run(async (context) =>
{
await context.Response.WriteAsync("Terminal Middleware Reached");
});
app.Run();
How would I pass a RequestDelegate in this call?
app.UseMiddleware<Capital>();