static void SerializeGltfAsset(Asset &asset, json &o) {
  if (!asset.generator.empty()) {
    SerializeStringProperty("generator", asset.generator, o);
  }

  if (!asset.copyright.empty()) {
    SerializeStringProperty("copyright", asset.copyright, o);
  }

  if (asset.version.empty()) {
    // Just in case
    // `version` must be defined
    asset.version = "2.0";
  }

  // TODO(syoyo): Do we need to check if `version` is greater or equal to 2.0?
  SerializeStringProperty("version", asset.version, o);

  if (asset.extras.Keys().size()) {
    SerializeValue("extras", asset.extras, o);
  }

  SerializeExtensionMap(asset.extensions, o);
}
static void SerializeGltfAsset(Asset &asset, json &o) {
  if (!asset.generator.empty()) {
    SerializeStringProperty("generator", asset.generator, o);
  }

  if (!asset.copyright.empty()) {
    SerializeStringProperty("copyright", asset.copyright, o);
  }

  if (asset.version.empty()) {
     
     
    asset.version = "2.0";
  }

   
  SerializeStringProperty("version", asset.version, o);

  if (asset.extras.Keys().size()) {
    SerializeValue("extras", asset.extras, o);
  }

  SerializeExtensionMap(asset.extensions, o);
}