Is there reason for the fact that in the REST module the update (PUT) method is implemented with url parameters and the the create (POST) as form data? I had to patch the module because the REST server in my case requires the form data also with the PUT method.
Chris de Gelder
I'm not sure about your exact question about the REST module, but did you try the native REST action available in Mendix 6.6? If you use it you can send form data with any REST verb by adding it to the headers.