@Override
    public String[] requiredModules() {
        return new String[]{CoreModule.NAME};
    }
Use Zookeeper to manage all instances in SkyWalking cluster.
oap-server/server-cluster-plugin/cluster-zookeeper-plugin/src/main/java/org/apache/skywalking/oap/server/cluster/plugin/zookeeper/ClusterModuleZookeeperProvider.java