presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/RaptorHandleResolver.java/RaptorHandleResolver/getTransactionHandleClass
class RaptorHandleResolver:    @Override
    public Class<? extends ConnectorTransactionHandle> getTransactionHandleClass()
    {
        return RaptorTransactionHandle.class;
    }