Changed: ICG sends now keep-alive packages to the devices (only for IGEL OS firmware 11.05.131 and higher) to detect and close dead websockets and forward the offline state of the device to UMS.
Added: REST endpoint to test the status of the ICG.
Changed: Updated bundled Zulu JRE from version 8u282 to 8u302.
Changed: Updated Spring Boot to version 2.5.6 (embedded Tomcat version 9.0.54).