public ServerBuilder accessLogger(Function<? super VirtualHost, ? extends Logger> mapper) {
        virtualHostTemplate.accessLogger(mapper);
        return this;
    }
Sets the default access logger mapper for all {@link VirtualHost}s.
The {@link VirtualHost}s which do not have an access logger specified by a {@link VirtualHostBuilder}
will have an access logger set by the {@code mapper} when {@link ServerBuilder#build()} is called.
core/src/main/java/com/linecorp/armeria/server/ServerBuilder.java