protected Client createHttpClient(final FessConfig fessConfig, final String host) {
        final String[] hosts =
                split(host, ",").get(stream -> stream.map(String::trim).filter(StringUtil::isNotEmpty).toArray(n -> new String[n]));
        final Builder builder = Settings.builder()
                .putList("http.hosts", hosts)
                .put("processors", fessConfig.availableProcessors())

    /** The key of the message: Permissions */
    public static final String LABELS_PERMISSIONS = "{labels.permissions}";

    /** The key of the message: Virtual Hosts */
    public static final String LABELS_virtual_hosts = "{labels.virtual_hosts}";

    /** The key of the message: Virtual Host */
    public static final String LABELS_virtual_host = "{labels.virtual_host}";