message: Use the default dataset magic value if the flag value is empty.
diff: @@ -443,7 +443,11 @@ int main(int argc, char **argv) {
  << "\nid.def: " << absl::GetFlag(FLAGS_id_def) << std::endl;
  absl::StatusOr<std::unique_ptr<mozc::DataManager>> data_manager =
  - mozc::DataManager::CreateFromFile(absl::GetFlag(FLAGS_engine_data_path),
  + absl::GetFlag(FLAGS_magic).empty()
  + ? mozc::DataManager::CreateFromFile(
  + absl::GetFlag(FLAGS_engine_data_path))
  + : mozc::DataManager::CreateFromFile(
  + absl::GetFlag(FLAGS_engine_data_path),
  absl::GetFlag(FLAGS_magic));
  CHECK_OK(data_manager);
  