void refresh() {
        if (Objects.isNull(clusterNodesQuery)) {
            this.clusterNodesQuery = moduleDefineHolder.find(ClusterModule.NAME)
                                                       .provider()
                                                       .getService(ClusterNodesQuery.class);
        }

        this.refresh(clusterNodesQuery.queryRemoteNodes());
    }
Refresh the remote clients by query OAP server list from the cluster module.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/remote/client/RemoteClientManager.java