[Snake1980]

Modified (without sleep for now) and I removed PIDFILE...

#! /bin/sh
# /etc/init.d/jdownloader
### BEGIN INIT INFO
# Provides: jDownloader2
# Required-Start: networking
# Required-Stop:
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: jDownloader2 Server Daemon
# Description: T_Send's Starts/Stops/Restarts/Status the jDownloader2 Server Daemon
### END INIT INFO
# Author: T_Send  Contact: t_send@itnu.pl  Web: www.itnu.pl

set -e
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
DESC="jDownloader2 Server"
NAME="jdownloader"
## USER for new files ownership & make sure USER has read/write permission to DOWNLOAD-DIR
USER=pi
GROUP=pi
UMASK=077
DIR="/home/pi/jdownloader2"
SCRIPT="/etc/init.d/$NAME"
#PIDFILE="$DIR/JDownloader.pid"
JAVA="/usr/lib/jvm/jdk-8-oracle-arm32-vfp-hflt/jre/bin/java"
PARM="-Djava.awt.headless=true -jar $DIR/JDownloader.jar"
STATUS="$JAVA $PARM"

. /lib/lsb/init-functions

start_daemon () {
        start-stop-daemon --start \
			--chuid $USER \
                        --group $GROUP \
                        --umask $UMASK \
			--oknodo \
			--background \
			--exec $JAVA -- $PARM
		log_end_msg $?
}

case "$1" in
    start)
        log_daemon_msg "Starting daemon" "$DESC "
        start_daemon
        ;;
    stop)
        log_daemon_msg "Stopping daemon" "$DESC "
        start-stop-daemon --stop
        log_end_msg $?
        ;;
    restart)
        log_daemon_msg "Restarting daemon" "$DESC "
        start-stop-daemon --stop
        log_end_msg $?
        start_daemon
        ;;
    status)
        status_of_proc "$STATUS" "$DESC " && exit 0 || exit $?
        ;;
    *)
        log_action_msg "Usage: $SCRIPT {start|stop|restart|status}" || true
        exit 2
        ;;
esac

exit 0

but when I shutdown...

Aug 26 23:48:03 snakeberry jdownloader[22983]: Stopping daemon: jDownloader2 Server start-stop-daemon: need at least one of -
Aug 26 23:48:03 snakeberry jdownloader[22983]: Try 'start-stop-daemon --help' for more information.
Aug 26 23:48:03 snakeberry systemd[1]: jdownloader.service: Control process exited, code=exited, status=3/NOTIMPLEMENTED
Aug 26 23:48:03 snakeberry systemd[1]: jdownloader.service: Failed with result 'exit-code'.
Aug 26 23:48:03 snakeberry systemd[1]: Stopped LSB: jDownloader2 Server Daemon.