@Override
    public List<VirtualHost> findVirtualHosts(HttpService service) {
        requireNonNull(service, "service");

        final Class<? extends HttpService> serviceType = service.getClass();
        final List<VirtualHost> res = new ArrayList<>();
        for (VirtualHost h : virtualHosts) {
            for (ServiceConfig c : h.serviceConfigs()) {
                // Consider the case where the specified service is decorated before being added.
                final HttpService unwrapped = c.service().as(serviceType);
                if (unwrapped == null) {
                    continue;
                }

                if (unwrapped == service) {
                    res.add(c.virtualHost());
                    break;
                }
            }
        }

        return res;
    }
Initialized later by {@link Server} via {@link #setServer(Server)}.
core/src/main/java/com/linecorp/armeria/server/DefaultServerConfig.java