setOnlyIf(element -> parentTask.get().getLicensesDir() != null);
    }

    @TaskAction
    public void updateShas() throws NoSuchAlgorithmException, IOException {
        Set<File> shaFiles = parentTask.get().getShaFiles();

        for (File dependency : parentTask.get().getDependencies()) {
            String jarName = dependency.getName();
            File shaFile = parentTask.get().getShaFile(jarName);

        return new LinkedHashMap<>(mappings);
    }

    File getShaFile(String jarName) {
        return new File(licensesDir, jarName + SHA_EXTENSION);
    }

    @Internal
    Set<File> getShaFiles() {
        File[] array = licensesDir.listFiles();
        if (array == null) {
            throw new GradleException("\"" + licensesDir.getPath() + "\" isn't a valid directory");
        }