--xYzZY
Content-Disposition: form-data; name="file_name"; filename="<path>/test.csv"
Content-Type: text/plain

<data here>

--xYzZY
Content-Disposition: form-data; name="import.x"

20
--xYzZY
Content-Disposition: form-data; name="import.y"

9
--xYzZY--