code: public static void checkGetInputStreamOK(Resource resource) throws IOException {
  	if (!resource.exists()) throw new IOException("file [" + resource.getPath() + "] does not exist");
  
  	if (resource.isDirectory()) throw new IOException("can't read directory [" + resource.getPath() + "] as a file");
  
      }
docs: check if getting a inputstream of the file is ok with the rules for the Resource interface, to
  not change this rules.
  
  @param resource
  @throws IOException