@Override
    public List<RemoteInstance> queryRemoteNodes() {
        if (remoteInstance == null) {
            return new ArrayList(0);
        }
        ArrayList remoteList = new ArrayList(1);
        remoteList.add(remoteInstance);
        return remoteList;
    }
A cluster manager simulator. Work in memory only. Also return the current instance.
oap-server/server-cluster-plugin/cluster-standalone-plugin/src/main/java/org/apache/skywalking/oap/server/cluster/plugin/standalone/StandaloneManager.java