Using HttpRequestFactory to jira xray's /rest/raven/1.0/import/execution/cucumber/multipart :
Map<String, Object> params = new HashMap<>();
params.put( "info", "zigouzi" );
params.put( "result", "baalo" );
HttpContent content = new UrlEncodedContent(params);
OAuthParameters oAuthParameters = jiraOAuthFactory.getParametersForRequest(ACCESS_TOKEN, CONSUMER_KEY, PRIVATE_KEY);
HttpRequestFactory requestFactory = new NetHttpTransport().createRequestFactory(oAuthParameters);
HttpRequest request = requestFactory.buildPostRequest(new GenericUrl(url), content);
request.getHeaders().setAccept("application/json");
String boundary = Long.toHexString(System.currentTimeMillis());
request.getHeaders().setContentType("multipart/form-data; boundary="+boundary);
request.getHeaders().setContentEncoding("application/json");
HttpResponse response = null ;
try
{
response = request.execute();
Scanner s = new Scanner(response.getContent()).useDelimiter("\\A");
result = s.hasNext() ? s.next() : "";
}
catch (Exception e)
{
}
did the trick.