Server side attachments and client side null values

[Da...@azetaedp.it]

Hi, I have a web service that accept request from a client, receiving a 
complex java object e returning another complex java object. The web 
service, also attach a huge xml file to the response message.
The problem is that if I don't attach any file, the client receive the 
correct java object, if I attach the file, the client receive the file 
correctly but the result of call.invoke is null.

This is the way I attach the file server side:

        MessageContext msgContext= MessageContext.getCurrentContext();
        Message response = msgContext.getResponseMessage();

        DataHandler buildFile = new DataHandler(new 
FileDataSource(toSend));
        AttachmentPart aPart = new AttachmentPart(buildFile);
        response.addAttachmentPart(aPart);
 
        response.saveChanges();

Can anyone help me?