@TestOnly
 public int countPointers() {
   int result = 0;
   for (TreeMap<String, VirtualFilePointerImpl> map : myUrlToPointerMaps.values()) {
     result += map.values().size();
   }
   return result;
 }
  public synchronized void assertPointersDisposed() {
    for (Map.Entry<VirtualFilePointerListener, TreeMap<String, VirtualFilePointerImpl>> entry :
        myUrlToPointerMaps.entrySet()) {
      VirtualFilePointerListener listener = entry.getKey();
      TreeMap<String, VirtualFilePointerImpl> map = entry.getValue();
      for (VirtualFilePointerImpl pointer : map.values()) {
        myUrlToPointerMaps.clear();
        pointer.throwNotDisposedError("Not disposed pointer: listener=" + listener);
      }
    }

    synchronized (myContainers) {
      if (!myContainers.isEmpty()) {
        VirtualFilePointerContainerImpl container = myContainers.iterator().next();
        myContainers.clear();
        throw new RuntimeException("Not disposed container " + container);
      }
    }
  }