in pom.xml file

       <profile>
            <id>h2</id>
            <properties>
                .....
                <jdbc.url>jdbc:h2:/tmp/${db.name};MVCC=TRUE</jdbc.url>
                ......
H2 supports table locks only (see Locking, Lock-Timeout, Deadlocks section of http://www.h2database.com/html/frame.html?features.html&main ). Row locks are in wish-list for next release: http://groups.google.com/group/h2-database/web/roadmap

If not MVCC model,it will report error on testSaveConflictingUser!!!