Okay, here you are…
crw-rw---- 1 root uucp 188, 0 7. Jan 16:49 /dev/ttyUSB0
drwxrwxr-x 2 root lock 40 7. Jan 17:46 /var/run/lock/lockdev/
$ id
uid=1001(openhab) gid=1001(openhab) Gruppen=1001(openhab),14(uucp),54(lock)
RXTXcomm works perfectly fine BTW…