* {@code
     * String username = f.getPrincipal().getName();
     * }
     * The {@code Principal} object returned will never be {@code null}
     * however the username can be {@code null} indication anonymous
     * credentials were used (e.g. some IPC$ services).
     */

    /**
     * Returns the principal used for authentication
     *
     * @return the authentication principal
     */