Hi,
I was not able to restart Jenkins on my CentOS 7 box by using systemctl, but it was ok after a server reboot.
I got a HTTP 503 error and NullPointerException into log file.
I was able to resolve this issue by installing dejavu-sans-fonts package, even on Java headless configuration.
I think it would be better to add a RPM dependency to dejavu-sans-fonts package (and also probably to fontconfig).
Regards.