no multipart boundary was found
For your eyes only, in java you might use :
String boundary = Long.toHexString(System.currentTimeMillis());
request.getHeaders().setContentType("multipart/form-data; boundary="+boundary);
It looks like you're not specifying a boundary in your HTTP request header - see here for what I mean Unable to send a multipart/mixed request to spring MVC based REST service
Content-Type: multipart/mixed;boundary=YourBoundaryOfChoiceHere