kubectl describe pod: use ReportingController as an event source

With https://github.com/kubernetes/kubernetes/pull/91645 merged (promotion of v1beta1 events to v1),
it's no longer permitted to set Source field.
Based on https://stupefied-goodall-e282f7.netlify.app/contributors/design-proposals/instrumentation/events-redesign/#backward-compatibility
Source.Component is supposed to be replaced by ReportingController.
Source.Host is supposed to be replaced by DeprecatedHost, though DeprecatedHost
was never implemented. Thus, ignoring the second field.

Kubernetes-commit: 71edf075de3ea0e26aa40f06f1670862aaebcf33

pkg/describe/describe.go

@@ -3873,11 +3873,15 @@ func DescribeEvents(el *corev1.EventList, w PrefixWriter) {
 				interval = translateMicroTimestampSince(e.EventTime)
 			}
 		}
+		source := e.Source.Component
+		if source == "" {
+			source = e.ReportingController
+		}
 		w.Write(LEVEL_1, "%v\t%v\t%s\t%v\t%v\n",
 			e.Type,
 			e.Reason,
 			interval,
-			formatEventSource(e.Source),
+			source,
 			strings.TrimSpace(e.Message),
 		)
 	}
@@ -5001,15 +5005,6 @@ func translateTimestampSince(timestamp metav1.Time) string {
 	return duration.HumanDuration(time.Since(timestamp.Time))
 }
 
-// formatEventSource formats EventSource as a comma separated string excluding Host when empty
-func formatEventSource(es corev1.EventSource) string {
-	EventSourceString := []string{es.Component}
-	if len(es.Host) > 0 {
-		EventSourceString = append(EventSourceString, es.Host)
-	}
-	return strings.Join(EventSourceString, ", ")
-}
-
 // Pass ports=nil for all ports.
 func formatEndpoints(endpoints *corev1.Endpoints, ports sets.String) string {
 	if len(endpoints.Subsets) == 0 {