@TestOnly
  void shelveAllPointersIn(@NotNull Runnable runnable) {
    FilePartNode[] oldChildren;
    //noinspection SynchronizeOnThis
    FilePartNodeRoot localRoot = myLocalRoot;
    synchronized (this) {
      oldChildren = localRoot.children;
      localRoot.children = FilePartNode.EMPTY_ARRAY;
    }
    try {
      runnable.run();
    }
    finally {
      //noinspection SynchronizeOnThis
      synchronized (this) {
        localRoot.children = oldChildren;
      }
    }
  }
@TestOnly
  void shelveAllPointersIn(@NotNull Runnable runnable)