How to use routing to add .html suffix?

Hi everybody.
I tried to use routing to add .html suffix .In router.php :

Code:

$routes->get('abc.html', 'Homepage::show_categories_page/abc');

I hope when I go to URL : mydomain.com/abc.html ,it would swich to above routes.But it redirect to / (index.php)

When I tried to remove .html suffix.It works perfectly 

Code:

$routes->get('abc', 'Homepage::show_categories_page/abc');

I noticed at CI 3,it can be add suffix though application/config/config.php :

Code:

$config['url_suffix'] = '.html';

But I found nothing similar as that file in CI 4.My question is how to use routing to add .html suffix?

Thank you all for your help.

Do you have any susggest?

Did you find any solution for this?

Haven't tried this, but I guess it's do to the fact it's interpreted as regex. So try escaping the wildcard dot.

Code:

$routes->get('abc\.html', 'Homepage::show_categories_page/abc');