The ACTUATION_FAILURE type should be used when we want to report
an error to the user indicating why the current number of workers
in the pool could not be changed.
Displayed in the current status and history widgets.
CurrentNumWorkersChanged
The CURRENT_NUM_WORKERS_CHANGED type should be used when actual worker
pool size has been changed, but the target_num_workers has not changed.
NoChange
Used when we want to report to the user a reason why we are
not currently adjusting the number of workers.
Should specify both target_num_workers, current_num_workers and a
decision_message.
TargetNumWorkersChanged
The TARGET_NUM_WORKERS_CHANGED type should be used when the target
worker pool size has changed at the start of an actuation. An event
should always be specified as TARGET_NUM_WORKERS_CHANGED if it reflects
a change in the target_num_workers.
TypeUnknown
Default type for the enum. Value should never be returned.