How to invoke graceful restart?

[Draghmar]

Hi. I've seen that there's this interesting peace of update happened recently. ;)
Support graceful restart for Coroutine\Http\Server. When server shutting down, the client connection will no longer be forcibly closed, and only stop listening to new requests
Is this something happening by default? If not then how could I use it? I'm using unit file to start server, which is based on something I found long time ago in the issue section:

[Unit]
Description=Test Swoole Service
After=network-online.target

[Service]
User=http
Group=http
ExecStart=/bin/php -n /*...Some extensions...*/ -d extension=swoole.so swoole.php
ExecStop=/bin/kill $MAINPID
ExecReload=/bin/kill -USR1 $MAINPID

[Install]
WantedBy=multi-user.target

Do I have to make some adjustments to make it work?