MANY THX, this DIR I also found, but I was not sure.
What I do step by step “for openhabian Users”:
connect via SSH to openhabian
echo -n | openssl s_client -servername fmipmobile.icloud.com -host fmipmobile.icloud.com -port 443 -prexit -showcerts 2>/dev/null | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > /tmp/icloud2.crt
cd /tmp
csplit -f cert /tmp/icloud2.crt '/^-----BEGIN CERTIFICATE-----/' {*}
sudo su
cd /usr/lib/jvm/zulu-embedded-8-armhf
bin/keytool -importcert -file /tmp/cert01 -alias icloudfmi1 -trustcacerts -keystore ./jre/lib/security/cacerts -storepass changeit
Trust the certificates with y
bin/keytool -importcert -file /tmp/cert02 -alias icloudfmi2 -trustcacerts -keystore ./jre/lib/security/cacerts -storepass changeit
Trust the certificates with y
systemctl stop openhab2
OPTIONAL
rm -r /var/lib/openhab2/cache/*
rm -r /var/lib/openhab2/tmp/*
reboot