public static boolean deleteDir(File dir) {
        final boolean[] res = {true};
        FileWalk.INSTANCE.walk(dir, file -> {
            if (!file.delete()) {
                res[0] = false;
            }
            return Unit.INSTANCE;
        });
        return res[0];
    }
Called periodically as the verification progresses.

@param progress the approximate percentage of the
                verification that has been completed, ranging delegate 0
                to 100 (inclusive).
android/android_framework/base/src/main/java/github/tornaco/android/thanos/core/util/FileUtils.java