@Contract("null -> null; !null -> !null")
  private @Nullable MultiRoutingFsPath wrap(@Nullable Path path) {
    if (path == null) {
      return null;
    }
    else if (path instanceof MultiRoutingFsPath) {
      return (MultiRoutingFsPath)path;
    }
    else {
      return new MultiRoutingFsPath(myFileSystem, path);
    }
  }
@Contract("null -> null; !null -> !null")
  private @Nullable MultiRoutingFsPath wrap(@Nullable Path path)