ADDITIONAL SYSTEM INFORMATION :
Mac OX Catalina 10.15 6
openjdk version "15" 2020-09-15
OpenJDK Runtime Environment (build 15+36-1562)
OpenJDK 64-Bit Server VM (build 15+36-1562, mixed mode, sharing)

A DESCRIPTION OF THE PROBLEM :
The dmg is not signed and therefore cannot submitted for notarization.
codesign -dvvvv JabRef-100.0.0.dmg reports:
JabRef-100.0.0.dmg: code object is not signed at all


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Build a modularized app for mac os both dmg and pkgc and test it for singing.

 /Library/Java/JavaVirtualMachines/jdk-15.jdk/Contents/Home/bin/jpackage --type pkg --dest /Users/christophs/workspace/jabref/build/distribution --name JabRef --app-version 100.0.0 --app-image /Users/christophs/workspace/jabref/build/distribution/JabRef.app --verbose --type dmg --vendor JabRef --app-version 100.0.0 --file-associations /Users/christophs/workspace/jabref/buildres/mac/bibtexAssociations.properties --resource-dir /Users/christophs/workspace/jabref/buildres/mac --mac-sign --mac-package-signing-prefix org.jabref --mac-signing-key-user-name "<redacted>"

codesign -dvvvv JabRef-100.0.0.dmg

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The dmg is signed correclty and can be notarized.

ACTUAL -
Codesign reports that the dmg is not signed at all.
Notarization returns error message:
     "path": "JabRef-100.0.0.dmg/JabRef.app/Contents/runtime/Contents/MacOS/libjli.dylib",
      "message": "The signature of the binary is invalid.",

FREQUENCY : always