gvNIX occ-checksum add-on allows to use Optimistic Concurrency Control without add a "version" persistent field to a entity.
This feature is really useful on project which has to use RE on legacy database and must left unchanged database schema.
This requires to add a String transient field to entity to hold computed checksum based on record contents.
When integration test is added to entities managed by this add-on some test (flushTest and mergeTest) has compilation errors because it uses the ">" comparator to check version field.
We need support version field of type String in integration fields.
I'll prepare a pull-request which solve this problem.