(MultipartRequest) Content-Transfer-Encoding header is probably unnecessary / wrong

[d3v-cl]

Usually an unnecessary header doesn't hurt. But in my case the browser aborts an xmlhttprequest:

XMLHttpRequest cannot load.... Request header field content-transfer-encoding is not allowed by Access-Control-Allow-Headers in preflight response.

Apparently Content-Transfer-Encoding is not a valid http header anyways:
stackoverflow

Response I got from the server when the Request method was OPTIONS:

HTTP/1.1 204 No Content
Date: Wed, 06 Jul 2016 18:27:29 GMT
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: GET, POST, DELETE, PUT
Access-Control-Allow-Headers: Content-Type, api_key, Authorization
Allow: OPTIONS,POST
Connection: close
Server: Jetty(9.2.9.v20150224)

[kevmoo]

@nex3 thoughts on this?

[nex3]

We definitely shouldn't be passing this as an HTTP header, but it looks like it is necessary as a header for a multipart chunk (see the HTML spec, which refers to RFC 2388).