Implicitly marking parameter $request as nullable is deprecated

Problem/Motivation

In PHP 8.4 it is deprecated to add a default value of a parameter as NULL, but not making it nullable.

Steps to reproduce

Try to run the module with PHP 8.4.

Proposed resolution

Mark the parameter as accepting null.

Remaining tasks

None.

User interface changes

n/a

API changes

n/a

Data model changes

n/a