@Override
    @Deprecated
    public VirtualHost findVirtualHost(String hostname) {
        if (virtualHostAndPortMapping == null) {
            return defaultVirtualHost;
        }
        final Mapping<String, VirtualHost> virtualHostMapping = virtualHostAndPortMapping.get(-1);
        return virtualHostMapping.map(hostname);
    }
Initialized later by {@link Server} via {@link #setServer(Server)}.
core/src/main/java/com/linecorp/armeria/server/DefaultServerConfig.java