Presently BulkApi.bulkDelete uses the DELETE HTTP verb with an entity body to supply the object names. We should consider using the equivalent and POST HTTP verb instead. The latter is better supported by some tools and proxies as discussed here:
Unfortunately Swift 1.8.0 (Havana) added support for DELETE and 1.11/1.12 (Icehouse?) added support for POST:
We might need some fallback or compatibility logic.