docs: private void lockSourceAndCopy(File sourceFile, File copyFile) {
      sourceFile.opened();
      ReadWriteLock sourceLock = sourceFile.contentLock();
      if (sourceLock != null) {
        sourceLock.readLock().lock();
      }
      ReadWriteLock copyLock = copyFile.contentLock();
      if (copyLock != null) {
        copyLock.writeLock().lock();
      }
    }