MQTT KPI Publisher - sha:35c4bfaf

Update log4j CVE-2021-44228

MQTT KPI Publisher - sha:d7a7aae1

Hotfix: Updated log4j from 2.14.1 to 2.15.0 (CVE-2021-44228) Log4Shell

- Critical security issue CVE-2021-44228 in log4j allows to execute
arbitrary code (see https://logging.apache.org/log4j/2.x/security.html)

MQTT KPI Publisher - sha:0d5dba3b

fix: Add author name to license

MQTT KPI Publisher - sha:b40485a7

Update documentation, use shutdown hook, build project with maven plu…