Multiple file upload, but only one file in request body

Multiple file upload seems to not be handled correctly. If a user selects multiple files to upload on a file input field, such as the following, then the request body will contain only one file associated with the input field.

<input multiple name="files" id="files" type="file">

From a quick look at the code, maybe this part should use HM.fromListWith (<>) and a HashMap Text [UploadedFile]?