code: public void downgradeLastInode() {
      Preconditions.checkState(endsInInode());
      Preconditions.checkState(!mEntries.isEmpty());
      Preconditions.checkState(mLockMode == LockMode.WRITE);
  
      InodeEntry last = (InodeEntry) mEntries.get(mEntries.size() - 1);
      LockResource lock = mInodeLockManager.lockInode(last.getInode(), LockMode.READ);
      last.getLock().close();
      mEntries.set(mEntries.size() - 1, new InodeEntry(lock, last.mInode));
      mLockMode = LockMode.READ;
    }
docs: Downgrades the last inode from a write lock to a read lock. The read lock is acquired before
  releasing the write lock.