The /api/frs_packages/{id}/frs_release
returns a single "collection" struct containing a "files" attribute hosting the collection.
Test with https://tuleap.net/api/frs_packages/1/frs_release.
What is the reason of this structure?
Returning directly the collection, as a JSON array, would simplify the processing of this result.
Furthemore, most of the API endpoints returning a collection return directly the collection.