OSB defaulting Content-Type to "multipart/related" in case of attachments

Question

I have scenario where I need to invoke a REST Webservice from OSB which accepts only media types which has "multipart/atom+xml". OSB is used for protocol transformation converting the SOAP request into the HTTP POST request with multipart. I have Proxy Service which will unwrap the message from the SOAP Body and post the same message into the payload of the Business Service and the attachment is passed 'as is' from the SOAP Service. The external REST Service Provider expects the media type to be "multipart/atom+xml", but in OSB when an attachment is present in the message, OSB is overrding the "Content-Type" proeprty to "multipart/related" inspite of me setting the "Content-Type" property of HTTP Transport Header in OSB and as result external RESTFUL Service is throwing "415-Unsupported Media Type" error. Below is the test results. One interesting thing is, it happens only when there is attachment present in the message. In case of a message which doesn't have attachment any "Content-Type" specified in the Transport Header is passed by the OSB to the external service. Any help is highly appreciated.
OSB Transport Header
Added the header <http:Content-Type>multipart/atom+xml</http:Content-Type>
Actual Raw Message
POST http://xxx7200:7004/XXXInterfaces/identify HTTP/1.1
Content-Type: multipart/related; type="text/plain"; start="<Root_-328322390>"; boundary=MIME_Boundary; charset=UTF-8
MIME-Version: 1.0
User-Agent: Java1.6.0_17
Host: xxx7200:7004
Accept: text/html, image/gif, image/jpeg, */*; q=.2
Proxy-Connection: Keep-Alive
Content-Length: 4823
Expected Raw Message
POST http://xxx7200:7004/XXXInterfaces/identify HTTP/1.1
Content-Type: multipart/atom+xml; boundary=MIME_Boundary;
User-Agent: Java1.6.0_17
Host: xxx7200:7004
Accept: text/html, image/gif, image/jpeg, */*; q=.2
Proxy-Connection: Keep-Alive
Content-Length: 4803
-KC
Edited by: 799459 on Apr 8, 2011 5:36 AM
Edited by: 799459 on Apr 8, 2011 7:02 AM
Edited by: 799459 on Apr 8, 2011 7:13 AM
Edited by: 799459 on Apr 8, 2011 7:14 AM

Answer 1

HTTP content-type header has the following limitation as per osb doc.
Oracle Service Bus run time may overwrite these headers in the binding layer when preparing the message for dispatch. If these headers are modified, $inbound and $outbound are updated accordingly. So what you are seeing may be working as designed. Cant the remote service accept the multi part related content type set up by osb ?