@Override
  @Internal
  public @NotNull UpdatableIndex<FileType, Void, FileContent, ?> createIndexImplementation(@NotNull FileBasedIndexExtension<FileType, Void> extension,
                                                                                           @NotNull VfsAwareIndexStorageLayout<FileType, Void> indexStorageLayout)
    throws StorageException, IOException {
    return USE_MAPPED_INDEX ? new MappedFileTypeIndex(extension) : new FileTypeMapReduceIndex(extension, indexStorageLayout);
  }
@Override
  @Internal
  public @NotNull UpdatableIndex<FileType, Void, FileContent, ?> createIndexImplementation(@NotNull FileBasedIndexExtension<FileType, Void> extension,
                                                                                           @NotNull VfsAwareIndexStorageLayout<FileType, Void> indexStorageLayout)