ctx.form().toMultiMap();

        @SuppressWarnings("null")
        Map<String, List<String>> formMultimap = form.toMultimap();
        /*
         * Undertow will randomly decide what fields get turned into a file. Its
         * completely unclear how it makes that decision but my guess is it is
         * based on some pool.
         * 
         * Thus we must extract the contents of multipart fields that have
         * become temp files.
         */
        var files = form.files();
        if (!files.isEmpty()) {
            formMultimap = new LinkedHashMap<String, List<String>>(formMultimap);
            for (var f : files) {
                String key = f.getName();
                // should check size to not blow up heap.
                String value = new String(f.bytes(), java.nio.charset.StandardCharsets.UTF_8);
                formMultimap.put(key, List.of(value));
            }
        }
        return formMultimap;