UUIDs are often used as identifiers in larger system where data crosses database boundaries (e.g. message driven infrastructure). Activiti support for UUIDs is limited to the standard serializable variable type, which is not queryable. So a specific UUIDType is neccessary to map UUIDw to Stringw, which is then queryable. My whish is to integrate a UUIDType into the core codebase due to the fact, that UUIDs are "standard" identifiers and should be fully supported out of the box. Patch and testcase are included.