Can't seed string sets

Looking for a way to add string sets to seeds, when putting this in an array it just seeds a list

Any ideas?

Start by locating the seed-handling entry point and tracing how arrays are converted into DynamoDB values. Compare the current list behavior with the representation required for string sets; done means seed definitions can create string sets rather than lists, with coverage for that case.

Written by the indexing model from the issue text.