When called from V3, controller calls V2s get_product_data method, where stock_status was did not existed and was renamed. In V3 controller, we compute it based on V2 in_stock field.
We are using func_get_arg method to receive argument in a backward compatible way since we cannot modify function signature to add more params even with default params. Earlier I was hoping to use DI to create another child class with modified signature and load it depending upon where we are executing from, however since we had to revert DI, we add this workaround to unblock #27735.
Peter Fabian
vedanshujain
Claudio Sanches