// RegisterEvent notifies the implementer of an xDS ACK, and must be non-blocking
	RegisterEvent(conID string, eventType EventType, nonce string)
	RegisterDisconnect(s string, types sets.Set[EventType])
	QueryLastNonce(conID string, eventType EventType) (noncePrefix string)

					ProxyID: con.proxy.ID,
					ClusterVersion: s.getResourceVersion(s.StatusReporter.QueryLastNonce(con.ID(), v3.ClusterType),
						resourceID, knownVersions),
					ListenerVersion: s.getResourceVersion(s.StatusReporter.QueryLastNonce(con.ID(), v3.ListenerType),
						resourceID, knownVersions),
					RouteVersion: s.getResourceVersion(s.StatusReporter.QueryLastNonce(con.ID(), v3.RouteType),
						resourceID, knownVersions),

		}
	}
	return res, nil
}

type distributionEvent struct {
	conID            string
	distributionType xds.EventType
	nonce            string
}

func (r *Reporter) QueryLastNonce(conID string, distributionType xds.EventType) (noncePrefix string) {
	key := GenStatusReporterMapKey(conID, distributionType)
	r.mu.RLock()
	defer r.mu.RUnlock()
	return r.status[key]
}

	s := xdsfake.NewFakeDiscoveryServer(t, xdsfake.FakeOptions{})
	expectNonce := func(nonce, ty string) {
		t.Helper()
		assert.EventuallyEqual(t, func() string {
			return s.Discovery.StatusReporter.QueryLastNonce("test.default-1", ty)
		}, nonce[:xds.VersionLen])
	}

	ledger := ledger.Make(time.Minute)
	ledger.Put("key", "value") // If there is no config, ledger would be empty
	s.Env().SetLedger(ledger)