fixup! fix: List no resources when source namespace is empty string

Return nil slice

Author: dlipovetsky

pkg/controllers/namespacesync/controller.go

@@ -153,7 +153,7 @@ func (r *Reconciler) listSourceClusterClasses(
 	// Handle the empty string explicitly, because listing resources with an empty
 	// string namespace returns resources in all namespaces.
 	if r.SourceClusterClassNamespace == "" {
-		return []clusterv1.ClusterClass{}, nil
+		return nil, nil
 	}
 
 	ccl := &clusterv1.ClusterClassList{}