@Override
  public @NotNull <K, V> Collection<VirtualFile> getContainingFiles(@NotNull ID<K, V> indexId,
                                                                    @NotNull K dataKey,
                                                                    @NotNull GlobalSearchScope filter) {
    return ContainerUtil.newHashSet(getContainingFilesIterator(indexId, dataKey, filter));
  }
@Override
  public @NotNull <K, V> Collection<VirtualFile> getContainingFiles(@NotNull ID<K, V> indexId,
                                                                    @NotNull K dataKey,
                                                                    @NotNull GlobalSearchScope filter)