code: public void sendFile(final String path,
                         final int max_age) throws IOException {
      sendFile(HttpResponseStatus.OK, path, max_age);
    }
docs: Send a file (with zero-copy) to the client with a 200 OK status.
  This method doesn't provide any security guarantee.  The caller is
  responsible for the argument they pass in.
  @param path The path to the file to send to the client.
  @param max_age The expiration time of this entity, in seconds.  This is
  not a timestamp, it's how old the resource is allowed to be in the client
  cache.  See RFC 2616 section 14.9 for more information.  Use 0 to disable
  caching.