public void assertSwitches(Set<String> expectedSwitches, ApplicationId application, ClusterSpec.Id cluster) {
        NodeList allNodes = nodeRepository.nodes().list();
        NodeList activeNodes = allNodes.owner(application).state(Node.State.active).cluster(cluster);
        assertEquals(expectedSwitches, switchesOf(activeNodes, allNodes));
    }
Returns the hosts from the input list which are not retired
node-repository/src/test/java/com/yahoo/vespa/hosted/provision/provisioning/ProvisioningTester.java