If a user is granted to UPDATE a task, the user is able to
- reassign the task to another user
- add/delete from the candidate group(s)/user(s)
- change the task's due date
- complete/submit the task
- claim the task
- there exists separate permissions
- one permission "TASK_WORK" to claim and complete/submit the task
- one permission "TASK_ASSIGN", which summarize the following actions: reassign the task, add/delete candidate groups/users, etc.
- the permissions can be set on task and process definition level
- the permission UPDATE includes both these other permissions.
- the implementation should be backward compatible