code: public static ServletRequest unwrapMultipart( ServletRequest request )
      {
          if ( request instanceof MultipartRequestWrapper )
          {
              request = ( ( MultipartRequestWrapper ) request ).getRequest();
          }
  
          return request;
      }
docs: If the given request is a MultipartRequestWrapper (Struts class that doesn't extend
  HttpServletRequestWrapper), return the wrapped request; otherwise, return the given request.