An alarm history entry indicating a description of the entry and the time that the entry occurred. If the entry corresponds to a state transition, such as OK to Firing, then the entry also includes a transition timestamp.
Description for this alarm history entry. Avoid entering confidential information.
Example 1 - alarm state history entry: `The alarm state is FIRING`
Example 2 - alarm state transition history entry: `State transitioned from OK to Firing`
Timestamp for this alarm history entry. Format defined by RFC3339.
Timestamp for the transition of the alarm state. For example, the time when the alarm transitioned from OK to Firing. Available for state transition entries only. Note: A three-minute lag for this value accounts for any late-arriving metrics.