private @NotNull ConcurrentMap<VirtualFile, PsiDirectory> getVFileToPsiDirMap() {
    ConcurrentMap<VirtualFile, PsiDirectory> map = myVFileToPsiDirMap.get();
    if (map == null) {
      map = ConcurrencyUtil.cacheOrGet(myVFileToPsiDirMap, ContainerUtil.createConcurrentSoftValueMap());
    }
    return map;
  }
private @NotNull ConcurrentMap<VirtualFile, PsiDirectory> getVFileToPsiDirMap()