void InitializeFromExisting ( const [FAssetRegistryState](API\Runtime\AssetRegistry\AssetRegistry\FAssetRegistryState) & Existing, const [FAssetRegistrySerializationOptions](API\Runtime\AssetRegistry\AssetRegistry\FAssetRegistrySerializationOptio-) & Options, [EInitializationMode](API\Runtime\AssetRegistry\AssetRegistry\FAssetRegistryState\EInitializationMode) InitializationMode )