@Override
    public boolean isClosing() {
        return startStop.isClosing();
    }
Returns a {@link EventLoop} from the worker group. This can be used for, e.g., scheduling background
tasks for the lifetime of the {@link Server} using
{@link EventLoop#scheduleAtFixedRate(Runnable, long, long, TimeUnit)}. It is very important that these
tasks do not block as this would block all requests in the server on that {@link EventLoop}.
core/src/main/java/com/linecorp/armeria/server/Server.java