How to set content type for multipart/form-data part?

I have a multi-part request with two parts, a file and json metadata. The "file" part I can set the content-type through the attachment, but the "json" part seems to be defaulting to application/octet-stream which causes a 415.

 

 

POST http://localhost:9080/foo HTTP/1.1
Accept-Encoding: gzip,deflate
Content-Type: multipart/form-data; boundary="----=_Part_16_1749562154.1557927365085"
MIME-Version: 1.0
Content-Length: 53766
Host: localhost:9080
Connection: Keep-Alive
User-Agent: Apache-HttpClient/4.5.2 (Java/1.8.0_181)


------=_Part_16_1749562154.1557927365085
Content-Disposition: form-data; name="json"

{ "foo" : "bar", "foo1" : "bar1" }
------=_Part_16_1749562154.1557927365085
Content-Type: image/jpeg
Content-Transfer-Encoding: binary
Content-Disposition: form-data; name="file"; filename="royal flush.jpg"

...

 

This causes a 415 Content type 'application/octet-stream' not supported.

 

Here is a snippet form the request (through Postman) which works:

 

Content-Disposition: form-data; name="json"
Content-Type: application/json
Content-Length: 608

{ "foo" : "bar", "foo1" : "bar1" }
--B7pQWGrOXLWmnqGJ6JvxJJWBMoXDNZn2H
Content-Disposition: form-data; name="file"
Content-Type: image/jpeg
Content-Length: 53275

...

 

When I change the content-type of the json part to application/octet-stream in Postman, I can reproduce the 415. So it seems if there is a way in ReadyAPI to set the content-type to application/json, I can POST successfully. But I do not see any options in ReadyAPI to do so.

 

Thanks for any help in advance!

Gene.