SOAP UI POST HTTP Request Form Fields

I want to upload a file using a POST http request in SOAP UI.

However, the servlet that answer to the upload of the file expect a sequence of form field items with only one item not being a form field (and being a file attachment). To give some background, we are using org.apache.commons.fileupload.servlet.ServletFileUpload to get the org.apache.commons.fileupload.FileItemStream which has the method isFormField().

Is there a way to send the a POST requests from SOAP UI without having the attachment as a form field?

Thanks in advance!