Inconsistency between specification and implementation: stimulus set CSV `filename` vs `stimulus_path_within_store`

The [BrainIO specification](https://github.com/brain-score/brainio/blob/main/docs/SPECIFICATION.md) says that the CSV file corresponding to a stimulus set must have a column called `filename` which refers to the filepath of the image within the store (or just the filename, if the store is flat). However, in the reference implementation of the spec, I see code referencing `stimulus_path_within_store`. Which of the two is supposed to be used?