It looks for the path in target/classes relative to the current working directory, which breaks
when you have a multi module project such as https://github.com/nresare/javapasswordsafe
When iconFile lookup fails it fails silently, with no indication that anything went wrong
The file is expected to be located resources, that gets copied to target/classes which gets
included in any jars built, resulting in two copies of the icon in the .app. If
appbundle-maven-plugin were to look for the directly in the project directory you could exclude
it from the jar. (As a datapoint, AppIcon.icns for i.e. Numbers.app is 331KiB)
There are a couple of issues with iconFile: