- Prerequirement: the stage instance or human task instance is in the "Enabled" state
- there exists Java Api method like "CaseService#activate(instanceId)"
- the stage instance or task instance is in the "Activated" state after the activation and
- in case of a HumanTask there exists a new user task and
- in case of a Stage the "ChildActivities" (ie. currently only Stages and HumanTasks) of the stage will be created and they are "Available", afterwards they move into the "Enabled"-State (current limitation: there does not happen any check whether the entry criterias - sentries - are satisfied, or the manual activiation is equal to false)
- expose the new Java Api in the REST Api