Undeclared dependency on the domain module causing 500 response

Problem/Motivation

Firstly, thank you for the very helpful module. The module has an undeclared dependency on the domain module (the use of use Drupal\domain\DomainRedirectResponse) in the RedirectResponseSubscriber.

Steps to reproduce

Require and enable the module.
Attempt to save the configuration form.
Receive a 500 exception as the class does not exist.

Proposed resolution

Either declare the dependency properly or remove it. I will use the module for a multi-site setup where the language negotiation is different on one of the sites. Therefore, I would prefer not to have the dependency on the domain module at all.

Remaining tasks

Determine the solution path and then create an MR.

User interface changes

None.

API changes

To be defined.

Data model changes

None.