@NotNull
  VfsData getVfsData() {
    VfsData data = mySegment.owningVfsData;
    PersistentFSImpl owningPersistentFS = data.owningPersistentFS();
    if (!owningPersistentFS.isOwnData(data)) {
      //PersistentFSImpl re-creates VfsData on (re-)connect
      throw new AssertionError("'Alien' file object: was created before PersistentFS (re-)connected " +
                               "(id=" + myId + ", parent=" + myParent + "), " +
                               "owningData: " + data + ", pFS: " + owningPersistentFS);
    }
    return data;
  }
@NotNull
  VfsData getVfsData()