if (form.jarFile == null) {
                    throwValidationError(messages -> messages.addErrorsPluginFileIsNotFound(GLOBAL, form.id), this::asListHtml);
                }
                if (!form.jarFile.getFileName().endsWith(".jar")) {
                    throwValidationError(messages -> messages.addErrorsFileIsNotSupported(GLOBAL, form.jarFile.getFileName()),

         * @param rootDir
         *            The root directory.
         */
        public JarFileTraverser(final JarFile jarFile, final String rootPackage, final String rootDir) {
            this.jarFile = jarFile;
            this.rootPackage = rootPackage;
            this.rootDir = rootDir;
        }

        /**
         * Constructs an instance.
         *
         * @param url

                    final JarURLConnection jarURLConnection = (JarURLConnection) resource.openConnection();
                    try (JarFile jarFile = jarURLConnection.getJarFile()) {
                        final Enumeration<JarEntry> entries = jarFile.entries();
                        while (entries.hasMoreElements()) {
                            final JarEntry entry = entries.nextElement();