@Override
  public void unregisterMetaData(@NotNull ConfigFileMetaData metaData) {
    boolean changed = myMetaData.remove(metaData);
    ConfigFileMetaData actual = myId2MetaData.remove(metaData.getId());
    changed |= (actual != null);
    if (changed) {
      myCachedMetaData = null;
    }
  }
@Override
  public void unregisterMetaData(@NotNull ConfigFileMetaData metaData)