We get the form key from task service likes following snipped code
for (Task task : getTaskService().createTaskQuery().taskCandidateGroupIn(candidateGroup).initializeFormKeys().list()) {
task.getFormKey()
....
....
...
}
but now for some special reason we wanna get the form key value from HistoricTaskInstance, and we try several ways to get it but all of them fail.
We are wondering that how we can get the form key value from completed task?