I’m struggle to implement upload nested array of file in fastapi.

Here a simple code

//router

router.post("/feature/create", dependencies=[Depends(credentials)])
async def create_feature(
   file: Annotated[list[list[UploadFile]], File(default_factory=list)],
   db: Session = Depends(get_session),
):
   import pdb
   pdb.set_trace()

In postman

However when i try access file variable in above code, its always got empty list(array).

any idea?? thanks in advance