code: public void start() throws IOException {
      server.start();
      logger.info("Server started, listening on " + port);
      Runtime.getRuntime().addShutdownHook(new Thread() {
        @Override
        public void run() {
          // Use stderr here since the logger may has been reset by its JVM shutdown hook.
          System.err.println("*** shutting down gRPC server since JVM is shutting down");
          RouteGuideServer.this.stop();
          System.err.println("*** server shut down");
        }
      });
    }
docs: Start serving requests.