Redmine

I'm attempting to fix the Redmine reminder plugin which, I assume, was working before this commit https://www.redmine.org/projects/redmine/repository/revisions/15688/diff/.

I've debugged the plugin and found the source of the problem but I'm unable to find any documentation around the implementation done in this plugin, and a way to set additional safe_attributes extending from Redmine::Hook::ViewListener. I have very limited Ruby & Rails experience, so please keep that in mind. The problem seems to be that the safe_attributes list in /app/models/user_preference.rb doesn't allow the data from the plugin hook to be persisted to the database.

If I add the fields that are posted to the controller to the model, the data is saved correctly. How does one extended the safe_attributes list in this case?

I would also like to know the following:
1. Is the plugin implementation outdated now that safe_attributes was added to the UserPreference model and does the plugin actually need to be reworked?
2. Is Redmine perhaps lacking support for plugins to automatically extend the safe_attributes list in some way?
3. Wouldn't this plugin functionality make sense to be implemented into Redmine directly to further improve upon #13307 instead of a separate plugin?

Thanks