- when a variable is set through API (Task API / Runtime API), a user operation log entry is written
Currently this variable change information resides in the table ACT_HI_DETAIL.
- link historic details to user operation log entries
- add a USER_ID_ column to ACT_HI_DETAIL. Might be either to implement than option one, but it is also less clear when the field should be populated (only when a variable is set via API, as with user operation logs, or whenever a historic detail is written in the context of a logged in user, e.g. by a java delegate, etc.)