How to sign a launcher created by jpackage on Windows?

jpackage can be run in two stages to allow you to apply changes to the app image structure before generating the installer.

First stage use target jpackage --type app-image with --dest and --name parameters to generate the application image as yourstage1.dir\Your App Name:

jpackage --type app-image --dest yourstage1.dir --name "Your App Name" ... etc

Modify the contents of the output folder as needed, such as signing executables. I have a Windows screensaver, so my build renames one .EXE with .SCR extension in this step.

Finally apply jpackage again with the target type appropriate for your environment using --type exe/msi/dmg with --app-image to read the app image folder created in the first stage. Example:

jpackage --type msi --app-image "yourstage1.dir/Your App Name" ... etc

You can add --dest dir to change where the MSI file is created.