Content-Type request header not being updated in time to include boundary information for multipart/form-data

When posting multipart/form-data to the server without pre-informing a boundary value, the provider OutMultiPartProvider is updating the request header to include the default boundary information after the connection had been established between client and server and the headers had already been sent.
In this scenario, the request header sent to the server is "Content-Type: multipart/form-data", instead of "Content-Type: multipart/form-data; boundary=simple boundary".

I wrote down this blog post explaining the situation in more detail and including examples: http://renatoc.wait4.org/2011/02/25/posting-multipartform-data-using-apache-wink/

It might be too soon, but my suggestion is: either make possible for providers to change the request headers prior to establishing the connection between client and server, or make the boundary definition mandatory, throwing an exception when not present.