The historyItemId of the corresponding item in the request, echoed back so callers can correlate response entries with request items by id.
The system-generated key for the history item. When isDuplicate is true, this is the key of the original entry, not a new one.
True if this item had already been recorded and no new AGENT_HISTORY event was created for it; false if a new event was created.
The outcome of appending a single history item from an update request's history batch.