Signing problems with Xpect

When i try to installed the signed artifacts from https://ci.eclipse.org/xpect/job/Xpect/job/master/lastSuccessfulBuild/artifact/org.eclipse.xpect.releng/p2-repository/target/repository/ into Eclipse 2022-03 M1 i am getting this warning

do you have an idea what causes this? in the log i can find

09:00:20  + gpg --batch --import ****
09:00:20  gpg: directory `/home/jenkins/.gnupg' created
09:00:20  gpg: new configuration file `/home/jenkins/.gnupg/gpg.conf' created
09:00:20  gpg: WARNING: options in `/home/jenkins/.gnupg/gpg.conf' are not yet active during this run
09:00:20  gpg: keyring `/home/jenkins/.gnupg/secring.gpg' created
09:00:20  gpg: keyring `/home/jenkins/.gnupg/pubring.gpg' created
09:00:20  gpg: key C1AA5FA7: secret key imported
09:00:20  gpg: /home/jenkins/.gnupg/trustdb.gpg: trustdb created
09:00:20  gpg: key C1AA5FA7: public key "Eclipse Xpect Project <xpect-dev@eclipse.org>" imported
09:00:20  gpg: Total number processed: 1
09:00:20  gpg:               imported: 1  (RSA: 1)
09:00:20  gpg:       secret keys read: 1
09:00:20  gpg:   secret keys imported: 1
09:00:20  ++ gpg --list-keys --with-colons