Dirk Heinrichs not be part of the Jenkins package, but the Tomcat one, right?
not Jenkins, nor Tomcat - environment specific configuration
Also, the "EnvironmentFile" entry is there for providing some kind of backwards compatibility with system v
wrong - this is not a backward compatibility level, but conscious way to pass basic deployment configuration instead of large unit file with tons of Environment definitions which will not be updated from place to place
In a pure systemd setup they shouldn't be used anymore as environment variables
wrong again - it's a just two different methods for environment configuration for 'pure' systemd setup
Customizations should then go into /etc/systemd/system/myservice.service.d/*.conf