[Metricbeat][Kubernetes] Share watchers between metricsets

go.mod

@@ -2,7 +2,6 @@ module github.com/elastic/beats/v7
 
 go 1.21
 
-// replace github.com/elastic/elastic-agent-autodiscover => /Users/michaliskatsoulis/go/src/github.com/elastic/elastic-agent-autodiscover
 require (
 	cloud.google.com/go/bigquery v1.55.0
 	cloud.google.com/go/monitoring v1.16.0

metricbeat/module/kubernetes/util/kubernetes.go

@@ -325,7 +325,7 @@
 }
 
 // addToMetricsetsUsing adds metricset identified by metricsetUsing to the list of resources using the shared watcher
-// identified by resourceName.
+// identified by resourceName. The caller of this function should be holding the lock.
 func addToMetricsetsUsing(resourceName string, metricsetUsing string, resourceWatchers *Watchers) {
 	resourceWatchers.lock.Lock()
 	defer resourceWatchers.lock.Unlock()
@@ -551,8 +551,8 @@
 		return &nilEnricher{}
 	}
 
 	var specificMetaGen metadata.MetaGen
 	var generalMetaGen *metadata.Resource
 	// Create the metadata generator to be used in the watcher's event handler.
 	// Both specificMetaGen and generalMetaGen implement Generate method for metadata collection.
 	if resourceName == ServiceResource || resourceName == PodResource {