Hi,
First of all, I would recommend updating to 5.0.0 now, as that is the latest stable release.
Not sure what you're asking though, the process instance id was added recently to the TaskSummary. I assume, based on what you are saying, that it wasn't implemented yet for CR1 and added afterwards for 5.0.0 and of course lives in the 5.1 SNAPSHOT releases as well.
Kris