docs: private void ensureInitialized() {
      if (!mInitialized) {
       lock.lock();
        try {
          if (!mInitialized) {
            mInternalPath = Environment.getDataDirectory();
            mExternalPath = Environment.getExternalStorageDirectory();
            updateStats();
            mInitialized = true;
          }
        } finally {
          lock.unlock();
        }
      }
    }