Only check cloudValue for overwriting

CHANGELOG.next.asciidoc

@@ -78,6 +78,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Add _bucket to histogram metrics in Prometheus Collector {pull}11578[11578]
 - Prevent the docker/memory metricset from processing invalid events before container start {pull}11676[11676]
 - Stop overwriting cloud.* fields from add_cloud_metadata if they are not empty. {pull}11612[11612] {issue}11305[11305]
+- Change `add_cloud_metadata` processor to not overwrite `cloud` field when it's already exist in the event. {pull}11612[11612] {issue}11305[11305]
 
 *Packetbeat*
 

libbeat/processors/add_cloud_metadata/add_cloud_metadata.go

@@ -361,12 +361,12 @@ func (p *addCloudMetadata) Run(event *beat.Event) (*beat.Event, error) {
 	// If cloud key exists in event already, this processor will not overwrite the cloud fields.
 	// For example aws module writes cloud.instance.* to events already, add_cloud_metadata should not overwrite these
 	// fields again.
-	cloudValue, err := event.GetValue("cloud")
-	if cloudValue != nil && err == nil {
-		return event, err
+	cloudValue, _ := event.GetValue("cloud")
+	if cloudValue != nil {
+		return event, nil
 	}
 
-	_, err = event.PutValue("cloud", meta)
+	_, err := event.PutValue("cloud", meta)
 
 	return event, err
 }