GET parameters that include dots cannot be checked in laravel

Question

I'm trying to determine whether a parameter is in the URL or not. I use:

$request->has('key');

And it's been working properly until now when I have to check wethere I have openid.ns parameter in the URL. If I remove the .(dot) everything works as expected, but:

URL: myhost.dev/auth/login?filter[openid.ns]=http://google.bg/

And then

dd($request->has('filter.openid.ns');

returns false.

What causes this odd behavior?