private Path asApplicationRelativePath(File file) {
            Path path = Path.fromString(file.toString());

            Iterator<String> pathIterator = path.iterator();
            // Skip the path elements this shares with the root
            for (Iterator<String> rootIterator = Path.fromString(root.toString()).iterator(); rootIterator.hasNext(); ) {
                String rootElement = rootIterator.next();
                String pathElement = pathIterator.next();
                if ( ! rootElement.equals(pathElement)) throw new RuntimeException("Assumption broken");
            }
            // Build a path from the remaining
            Path relative = Path.fromString("");
            while (pathIterator.hasNext())
                relative = relative.append(pathIterator.next());
            return relative;
        }
Strips the application package root path prefix from the path of the given file
config-model/src/main/java/com/yahoo/config/model/test/MockApplicationPackage.java