LabelSelectorRequirement

use-label-selector-requirement.go

	cms := &v1.ConfigMapList{}
 	requirement, err := labels.NewRequirement(
 		apis.LabelKey,
 		selection.Exists,
 		nil,
 	)
 	if err != nil {
 		return nil, err
 	}
 	ls := labels.NewSelector().Add(*requirement)
 	if err := c.List(context.Background(), cms,
 		client.InNamespace(cmns),
 		client.MatchingLabelsSelector{Selector: ls},
 	); err != nil {
 		return nil, err
 	}