Services remain in failed state after stopped with systemctl

Exit code 143 means that the program received a SIGTERM signal to instruct it to exit. The JVM catches the signal, does a clean shutdown, i.e. it runs all registered shutdown hooks, but still exits with an exit code of 143. That's just how Java works.

You should be able to suppress this by adding the exit code into the unit file as a "success" exit status:

[Service]
SuccessExitStatus=143

To complement Michael's answer, the exit code 143 is normal here, it is the way that the java VM received a SIGTERM signal, send by systemd to stop the process. The SIGTERM signal has a numeric value of 15 ( see man signal).

Now according to the Posix specification, "The exit status of a command that terminated because it received a signal shall be reported as greater than 128". (http://pubs.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html#tag_02_08_02)

Here the Java VM adds 128 + 15 and you get this exit code of 143.

This non zero exit code here make senses, as this allows to see that your java program exited because of an external signal, and you get a chance to find out which signal.