@Override
  public void save(@NotNull DataOutput out, @NotNull Collection<K> value) throws IOException {
    try {
      myKeyCollectionExternalizer.save(out, value);
    }
    catch (IllegalArgumentException e) {
      throw new IOException("Error saving data for index " + myIndexId, e);
    }
  }
@Override
  public void save(@NotNull DataOutput out, @NotNull Collection<K> value)