code: func (c *clientWrapper) lookupNamespace(ns string) string {
  	if c.isNamespaceAll {
  		return metav1.NamespaceAll
  	}
  	return ns
  }
docs: // lookupNamespace returns the lookup namespace key for the given namespace.
  // When listening on all namespaces, it returns the client-go identifier ("")
  // for all-namespaces. Otherwise, it returns the given namespace.
  // The distinction is necessary because we index all informers on the special
  // identifier iff all-namespaces are requested but receive specific namespace
  // identifiers from the Kubernetes API, so we have to bridge this gap.