Specifies an array of labels and label values. If a match is found, then routes with the matching label(s) are allowed to attach to the `Gateway`. This selector can contain any arbitrary key/value pair.
In the following example, routes in namespaces that have a `bar` label are allowed to attache to the `Gateway`.
In the following example, routes in namespaces that have a `bar` label are allowed to attach to the `Gateway`.