public CompletableFuture<Void> stop() {
        return startStop.stop();
    }
Stops this {@link Server} to close all active {@link ServerPort}s. Note that the shutdown procedure is
asynchronous and thus this method returns immediately. To wait until this {@link Server} is fully
shut down, wait for the returned {@link CompletableFuture}:
<pre>{@code
Server server = ...;
server.stop().get();
}</pre>
core/src/main/java/com/linecorp/armeria/server/Server.java