Get the notification policy tree.

Matchers is a slice of Matchers that is sortable, implements Stringer, and provides a Matches method to match a LabelSet against all Matchers in the slice. Note that some users of Matchers might require it to be sorted.

Matchers is a slice of Matchers that is sortable, implements Stringer, and provides a Matches method to match a LabelSet against all Matchers in the slice. Note that some users of Matchers might require it to be sorted.