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();

    protected void appendJarFile(final String cpSeparator, final StringBuilder buf, final File libDir, final String basePath) {
        final File[] jarFiles = libDir.listFiles((FilenameFilter) (dir, name) -> name.toLowerCase().endsWith(".jar"));
        if (jarFiles != null) {
            for (final File file : jarFiles) {
                buf.append(cpSeparator);
                buf.append(basePath);
                buf.append(file.getName());

            final List<Artifact> list = new ArrayList<>(jarFiles.length);
            for (final File file : jarFiles) {
                list.add(getArtifactFromFileName(artifactType, file.getName()));
            }
            list.sort(Comparator.comparing(Artifact::getName));
            return list.toArray(new Artifact[list.size()]);
        }

        final File[] jarFiles = ResourceUtil.getPluginJarFiles(artifactType.getId());