Karate multipart file array uses deprecated multipart/mixed content-type - karate

Question

When I upload an array of files as below
Given path 'files', 'multiple'
And multipart file files = { read: 'test.pdf', filename: 'upload-name1.pdf', contentType: 'application/pdf' }
And multipart file files = { read: 'test.pdf', filename: 'upload-name2.pdf', contentType: 'application/pdf' }
When method post
Then status 202
The files are added using the multipart/mixed content type eg:
Content-Type: multipart/form-data; boundary=176626466ce00050
--176626466ce00050
content-disposition: form-data; name="files"
content-type: multipart/mixed; boundary=892503f32da73ceb
--892503f32da73ceb
content-disposition: attachment; filename="upload-name1.pdf"
content-type: application/pdf
content-transfer-encoding: binary
...
--892503f32da73ceb
content-disposition: attachment; filename="upload-name2.pdf"
content-length: 553202
content-type: application/pdf
content-transfer-encoding: binary
...
--892503f32da73ceb--
--176626466ce00050
multipart/mixed was defined in RFC2388 but was later deprecated in RFC7578 so some servers such as Jetty will not support it.
Is it possible to override the default behaviour and use multiple form-data Content-Dispositions instead?
I am using Karate 1.3.0 and am pretty sure this wasn`t an issue with earlier versions

Answer 1

I'm unable to simulate this, so maybe you should follow this process: https://github.com/karatelabs/karate/wiki/How-to-Submit-an-Issue
This is what I tried:
* url 'https://httpbin.org/post'
* multipart file foo1 = { read: 'test.pdf', contentType: 'application/pdf' }
* multipart file foo2 = { read: 'test.pdf', contentType: 'application/pdf' }
* method post
You can see from the response that the server detects 2 multi-part files and it all looks ok.
I also see Karate print this in place of the request payload:
Mixed: content-disposition: form-data; name="foo1"; filename="test.pdf"
content-type: application/pdf; charset=UTF-8
content-length: 6514
Completed: true
IsInMemory: true
Mixed: content-disposition: form-data; name="foo2"; filename="test.pdf"
content-type: application/pdf; charset=UTF-8
content-length: 6514
Completed: true
IsInMemory: true
So it looks ok to me or unable to replicate. We simply use Netty to build multi-part payloads. You are welcome to dig into the code and recommend (or contribute a PR) in case we are using Netty wrong or if Netty has a bug.
For completeness, 1.3.1 has an alternate way of supporting an array of files, so you can try this approach:
* url 'https://httpbin.org/post'
# just use the same name, and behind the scenes an array of multi-parts will be sent in the request body
* def first = { name: 'foo', read: 'test.pdf', contentType: 'application/pdf' }
* def second = { name: 'foo', read: 'test.pdf', contentType: 'application/pdf' }
# note how we support an array of files, which can be programmatically built
# here we use enclosed javascript (refer docs) for convenience, note the round-brackets
* multipart files ([ first, second ])
* method post