@Override
    public String toString() {
        return "GremlinServer " + settings.host + ":" + settings.port;
    }
Stop Gremlin Server and free the port binding. Note that multiple calls to this method will return the
same instance of the {@code CompletableFuture}.
gremlin-server/src/main/java/org/apache/tinkerpop/gremlin/server/GremlinServer.java