In JBPM-1849, Thomas enumerated the current incompatibilites against 3.2.2. One of them is:

< create table JBPM_VARIABLEINSTANCE (... STRINGVALUE_ varchar(4000) null, ...)
> create table JBPM_VARIABLEINSTANCE (... STRINGVALUE_ varchar(255) null, ...)

The new type should be text, not varchar. This is related to the fact that the STRINGVALUE_ column is shared between StringInstance.hbm.xml and HibernateStringInstance.hbm.xml, both in modules/core/src/main/resources/org/jbpm/context/exe/variableinstance/. HibernateStringinstance.hbm.xml does not specify type="text".