Collection<DrillbitEndpoint> endpoints = clusterCoordinator.getAvailableEndpoints();
checkState(!endpoints.isEmpty(), "No DrillbitEndpoint can be found");
// just use the first endpoint for now
DrillbitEndpoint endpoint = endpoints.iterator().next();
this.client = new UserClient(supportComplexTypes, allocator,
TransportCheck.createEventLoopGroup(config.getInt(ExecConstants.CLIENT_RPC_THREADS), "Client-"));
logger.debug("Connecting to server {}:{}", endpoint.getAddress(), endpoint.getUserPort());
connect(endpoint);
connected = true;
}