func (c Clusters) Primaries(excluded ...Cluster) Clusters {
	return c.filterClusters(func(cc Cluster) bool {
		return cc.IsPrimary()
	}, exclude(excluded...))
}

// Exclude returns all clusters not given as input.
func (c Clusters) Exclude(excluded ...Cluster) Clusters {
	return c.filterClusters(func(cc Cluster) bool {
		return true
	}, exclude(excluded...))
}

				Instances: instances,
				Configs:   cfgs,
			})
			clusters := cg.Clusters(cg.SetupProxy(nil))
			xdstest.ValidateClusters(t, clusters)
			if c.filter != nil {
				clusters = xdstest.FilterClusters(clusters, c.filter)
			}
			g.Expect(len(clusters)).ShouldNot(Equal(0))

			for _, cluster := range clusters {
				g.Expect(cluster.CircuitBreakers).NotTo(BeNil())

					}
					return m
				}(),
			})
			sim := simulation.NewSimulationFromConfigGen(t, s, s.SetupProxy(tt.proxy))

			clusters := xdstest.FilterClusters(sim.Clusters, func(c *cluster.Cluster) bool {
				return strings.HasPrefix(c.Name, "inbound")
			})
			if len(s.PushContext().ProxyStatus) != 0 {
				// TODO make this fatal, once inbound conflict is silenced