return nameSet.stream().sorted().collect(Collectors.toList());
        }
        for (final File jarFile : jarFiles) {
            try (FileSystem fs = FileSystems.newFileSystem(jarFile.toPath(), ClassLoader.getSystemClassLoader())) {
                final Path xmlPath = fs.getPath("fess_ds++.xml");
                if (!Files.exists(xmlPath)) {
                    if (logger.isDebugEnabled()) {