Fix event time calculation on docker events (elastic#24318)

(cherry picked from commit 8b673e6)

CHANGELOG.next.asciidoc

@@ -112,6 +112,30 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add service resource in k8s cluster role. {pull}20546[20546]
 - [Metricbeat][Kubernetes] Change cluster_ip field from ip to keyword. {pull}20571[20571]
 - The `o365input` and `o365` module now recover from an authentication problem or other fatal errors, instead of terminating. {pull}21258[21258]
+- Rename cloud.provider `az` value to `azure` inside the add_cloud_metadata processor. {pull}20689[20689]
+- Add missing country_name geo field in `add_host_metadata` and `add_observer_metadata` processors. {issue}20796[20796] {pull}20811[20811]
+- [Autodiscover] Handle input-not-finished errors in config reload. {pull}20915[20915]
+- Explicitly detect missing variables in autodiscover configuration, log them at the debug level. {issue}20568[20568] {pull}20898[20898]
+- Fix `libbeat.output.write.bytes` and `libbeat.output.read.bytes` metrics of the Elasticsearch output. {issue}20752[20752] {pull}21197[21197]
+- The `o365input` and `o365` module now recover from an authentication problem or other fatal errors, instead of terminating. {pull}21259[21258]
+- Orderly close processors when processing pipelines are not needed anymore to release their resources. {pull}16349[16349]
+- Fix memory leak and events duplication in docker autodiscover and add_docker_metadata. {pull}21851[21851]
+- Fixed documentation for commands in beats dev guide {pull}22194[22194]
+- Fix parsing of expired licences. {issue}21112[21112] {pull}22180[22180]
+- Fix duplicated pod events in kubernetes autodiscover for pods with init or ephemeral containers. {pull}22438[22438]
+- Fix FileVersion contained in Windows exe files. {pull}22581[22581]
+- Fix index template loading when the new index format is selected. {issue}22482[22482] {pull}22682[22682]
+- Periodic metrics in logs will now report `libbeat.output.events.active` and `beat.memstats.rss`
+  as gauges (rather than counters). {pull}22877[22877]
+- Use PROGRAMDATA environment variable instead of C:\ProgramData for windows install service {pull}22874[22874]
+- Fix reporting of cgroup metrics when running under Docker {pull}22879[22879]
+- Fix typo in config docs {pull}23185[23185]
+- Fix `nested` subfield handling in generated Elasticsearch templates. {issue}23178[23178] {pull}23183[23183]
+- Fix CPU usage metrics on VMs with dynamic CPU config {pull}23154[23154]
+- Add FAQ entry for madvdontneed variable {pull}23429[23429]
+- Fix panic due to unhandled DeletedFinalStateUnknown in k8s OnDelete {pull}23419[23419]
+- Fix error loop with runaway CPU use when the Kafka output encounters some connection errors {pull}23484[23484]
+- Fix issue discovering docker containers and metadata after reconnections {pull}24318[24318]
 
 *Auditbeat*
 

libbeat/common/docker/watcher.go

@@ -276,7 +276,11 @@ func (w *watcher) watch() {
 			select {
 			case event := <-events:
 				w.log.Debugf("Got a new docker event: %v", event)
-				lastValidTimestamp = time.Unix(event.Time, event.TimeNano)
+				if event.TimeNano > 0 {
+					lastValidTimestamp = time.Unix(0, event.TimeNano)
+				} else {
+					lastValidTimestamp = time.Unix(event.Time, 0)
+				}
 				lastReceivedEventTime = w.clock.Now()
 
 				switch event.Action {