Cannot index enum type with Hibernate Search MassIndexer - hibernate-search

Question

#Entity
#Table(name = "asset")
#Indexed(index = "asset")
#Analyzer(impl = IKAnalyzer.class)
public class Asset {
#Column(name = "asset_name", length = 128, nullable = false)
#Field(name = "asset_name", index = Index.TOKENIZED, store = Store.YES)
private String assetName;
#Column(name = "type", length = 32, nullable = false)
#Enumerated(value = EnumType.STRING)
#Field(name = "type", index = Index.TOKENIZED, store = Store.YES)
private AssetTypeEnum type;
}
This is my configuration of hibernate search. The AssetTypeEnum is Enum type. I want to index the existed data in database. This is the code
Session session = sessionFactory.openSession();
FullTextSession fullTextSession = Search.getFullTextSession(session);
Transaction tx = fullTextSession.beginTransaction();
fullTextSession.createIndexer(Asset.class)
.batchSizeToLoadObjects(25)
.cacheMode(CacheMode.IGNORE)
.threadsToLoadObjects(5)
.threadsForSubsequentFetching(20)
.startAndWait();
tx.commit();
session.close();
It has no problem when I create a new asset, the asset can index auto. But I can not index with the enum type for the existed data in db. and if I remove the enum type it can work.
Does anyone meet this problem? thank you.