void writeConfigToDisk() {
        VespaTlsConfig config = VespaZookeeperTlsContextUtils.tlsContext()
                                                             .map(ctx -> new VespaTlsConfig(ctx, TransportSecurityUtils.getInsecureMixedMode()))
                                                             .orElse(VespaTlsConfig.tlsDisabled());
        writeConfigToDisk(config);
    }
@Test(expected = RuntimeException.class)
    public void require_that_this_id_must_be_present_amongst_servers() {
        ZookeeperServerConfig.Builder builder = new ZookeeperServerConfig.Builder();
        builder.zooKeeperConfigFile(cfgFile.getAbsolutePath());
        builder.server(newServer(1, "bar", 234, 432, false));
        builder.server(newServer(2, "baz", 345, 543, false));
        builder.myid(0);
        new Configurator(builder.build()).writeConfigToDisk(VespaTlsConfig.tlsDisabled());
    }