private String readPatch(ServletInputStream requestStream, String contentType)
     throws IOException {
   // fast forward stream past multi-part header
   int boundaryOff = contentType.indexOf("boundary="); // $NON-NLS-1$
   String boundary =
       contentType.substring(
           boundaryOff + "boundary=".length(), contentType.length()); // $NON-NLS-1$
   Map<String, String> parts = IOUtilities.parseMultiPart(requestStream, boundary);
   if ("fileRadio".equals(parts.get("radio"))) // $NON-NLS-1$ //$NON-NLS-2$
   return parts.get("uploadedfile"); // $NON-NLS-1$
   if ("urlRadio".equals(parts.get("radio"))) // $NON-NLS-1$ //$NON-NLS-2$
   return fetchPatchContentFromUrl(parts.get("url")); // $NON-NLS-1$
   return null;
 }