@Nullable
  public TrackerClient getTrackerClient(Request request,
                                        RequestContext requestContext,
                                        Ring<URI> ring,
                                        Map<URI, TrackerClient> trackerClients)
  {
    TrackerClient trackerClient;

    URI targetHostUri = KeyMapper.TargetHostHints.getRequestContextTargetHost(requestContext);

    if (targetHostUri != null)
    {
      trackerClient = getTrackerClientFromTarget(targetHostUri, requestContext, trackerClients);
    }
    else
    {
      trackerClient = getTrackerClientFromRing(request, requestContext, ring, trackerClients);
    }
    addToExcludedHosts(trackerClient, requestContext);

    return trackerClient;
  }
@Test
  public void testGetHostFromRing()
  {
    TrackerClient trackerClient = _clientSelector.getTrackerClient(_request, _requestContext, DEFAULT_RING, DEFAULT_TRACKER_CLIENT_MAP);
    assertTrue(DEFAULT_TRACKER_CLIENT_MAP.containsKey(trackerClient.getUri()));
  }