Allow other modules to alter parameters

As you might have guessed, Steve is no longer actively working on this. But I might pick it up for him :)

james.williams → changed the visibility of the branch 3264483-allow-other-modules to hidden.

OK; I've opened MR !2 which uses a modern event instead of a hook, which I believe does the trick. That said, I can't easily test it as my client doesn't have a easily-usable test environment. I can certainly get as far as the initial KBC offsite payment page, and parameters altered via this method do indeed get passed along as intended, I just can't then actually proceed from my local test site.

Thanks for the MR, it looks okay (I can't easily test it either), so I merged it.

Automatically closed - issue fixed for 2 weeks with no activity.