Added some comment related the controller field

pkg/cache/placeholder.go

@@ -47,6 +47,12 @@ type Placeholder struct {
 
 func newPlaceholder(placeholderName string, app *Application, taskGroup v1alpha1.TaskGroup) *Placeholder {
 	ownerRefs := app.placeholderOwnerReferences
+	// we need to set the controller field to false, because since we don't know what exactly the controller will do,
+	// we might have some unexpected behaviour.
+	// For example if it is a replication controller, some pods (placeholders and/or real pods) might be deleted
+	// in order to met the requested replication factor.
+	// Since we need the owner reference only for having the placeholders garbage collected,
+	// we can just set the controller field = false, so we can avoid any kind of side effects.
 	controller := false
 	for _, r := range ownerRefs {
 		*r.Controller = controller