Feature Request: Preserve EndsAt timestamp in Webhook payloads instead of resetting to zero value

[bohub12]

Proposal

Description

I've noticed that Alertmanager explicitly resets the EndsAt field to a zero value (0001-01-01T00:00:00Z) when sending webhook payloads for alerts that are not yet resolved.

Technical Observation

The current logic specifically clears the EndsAt value as follows:

	for _, alert := range alerts {
		a := *alert
		// Ensure that alerts don't resolve as time move forwards.
		if a.ResolvedAt(now) {
			resolvedSlice = append(resolvedSlice, &a)
		} else {
			a.EndsAt = time.Time{}
		}
		alertsSlice = append(alertsSlice, &a)
	}

Question & Curiosity

I found that this behavior has been discussed in several previous issues:

• Webhooks for firing alerts contain zeroed EndsAt #3351
• Alertmanager sending "empty" endsAt to webhook when alert is not resolved. #3341

Since these discussions have been around for a while without a change in the implementation, I’m curious if there’s a specific technical reason or a design philosophy behind keeping this as a zero value. Is this behavior intentionally maintained to avoid specific side effects that I might be overlooking? Or is there a concern that exposing this value might lead to inconsistent states in external integrations?