@VisibleForTesting
    public void waitForEachEventLoop() throws InterruptedException, ExecutionException {
        for (EventExecutor exec : serverGroup.clientToProxyWorkerPool) {
            exec.submit(() -> {
                        // Do nothing.
                    })
                    .get();
        }
    }
Use {@link #Server(Registry, ServerStatusManager, Map, ClientConnectionsShutdown, EventLoopGroupMetrics,
EventLoopConfig)}
instead.
zuul-core/src/main/java/com/netflix/zuul/netty/server/Server.java