The user upgraded transformers and the API got reworked — ProcessorMixin
no longer exposes 'attributes' / 'optional_attributes' as data classvars
(replaced by methods like get_attributes()). Our shim was unconditionally
patching ProcessorMixin.__init__ and crashing on AttributeError when its
inner code referenced cls.optional_attributes.
Skip the entire patch on transformers 5.x where the old classvars are
absent — the new release auto-derives attributes natively, no shim needed.
Same gate-by-feature-detection logic as the other shims in this function.
Federico Volovnik-Jose
6c3bb212e9