@Nullable <K, V> UpdatableIndex<K, V, FileContent, ?> getIndex(@NotNull ID<K, V> indexId) {
    assert myFreezed;
    final Pair<UpdatableIndex<?, ?, FileContent, ?>, FileBasedIndex.InputFilter> pair = myIndices.get(indexId.getUniqueId());

    //noinspection unchecked
    return (UpdatableIndex<K, V, FileContent, ?>)Pair.getFirst(pair);
  }
@Nullable <K, V> UpdatableIndex<K, V, FileContent, ?> getIndex(@NotNull ID<K, V> indexId)