in src/main/java/org/apache/netbeans/nbpackage/appimage/AppImageTask.java [54:72]
protected void customizeImage(Path image) throws Exception {
Path usrLib = image.resolve("usr").resolve("lib");
String execName = findLauncher(
usrLib.resolve("APPDIR").resolve("bin"))
.getFileName().toString();
Path appDir = usrLib.resolve(execName);
Files.move(usrLib.resolve("APPDIR"), appDir);
Path usrBin = image.resolve("usr").resolve("bin");
Files.createDirectories(usrBin);
Files.createSymbolicLink(usrBin.resolve(execName),
usrBin.relativize(appDir.resolve("bin").resolve(execName)));
setupIcons(image, execName);
setupDesktopFile(image, execName);
setupAppRunScript(image, execName);
}