public static List<String> getFilenamesForDirnameFromCP(String directoryName) throws
            URISyntaxException, IOException {
        List<String> filenames = new ArrayList<>();

        URL url = CustomContainersMainClass.class.getClassLoader().getResource(directoryName);

        if (url != null) {
            if (url.getProtocol().equals("file")) {
                File file = Paths.get(url.toURI()).toFile();
                if (file != null) {
                    File[] files = file.listFiles();
                    if (files != null) {
                        for (File filename : files) {
                            filenames.add(filename.toString());
                        }
                    }
                }
            } else if (url.getProtocol().equals("jar")) {
                String dirname = directoryName + "/";
                String path = url.getPath();
                String jarPath = path.substring(5, path.indexOf("!"));
                try (JarFile jar = new JarFile(URLDecoder.decode(jarPath, StandardCharsets.UTF_8.name()))) {
                    Enumeration<JarEntry> entries = jar.entries();
                    while (entries.hasMoreElements()) {
                        JarEntry entry = entries.nextElement();
                        String name = entry.getName();
                        //System.out.println("name " + name + "entry " + entry + jarPath);
                        if (name.startsWith(dirname) && !dirname.equals(name)) {
                            URL resource = CustomContainersMainClass.class.getClassLoader().getResource(name);
                            if (resource != null) {
                                filenames.add(name);
                            } else
                                Common.log("Missing files in plugins/" + CustomContainersMainClass.getInstance() + ".jar/" + directoryName + "/, contact the author of " + CustomContainersMainClass.getInstance().getName() + ".");
                        }
                    }
                }
            }
        }
        return filenames;
    }