If the hostname does not contains dot or is not localhost, NetUtils.createSocketAddr calls SecurityUtil.getByNameWithSearch(String) and it adds trailing dot to the hostname (please see Javadoc of SecurityUtil.getByExactName for the detail) and then resolve the hostname. In the environment, "af73ca3dfb64." (with trailing dot) cannot be resolved, so the error occurs.
Replacing the above code with
final InetSocketAddress addr =
new InetSocketAddress(nodeId.getHost(), nodeId.getPort());
fixes the error.