@Override
      public Object call() {
        Region<CustId, Customer> pr = getCache().getRegion(CUSTOMER);
        Region<String, String> r = getCache().getRegion(D_REFERENCE);
        pr.getAttributesMutator().addCacheListener(new ClientListener());
        r.getAttributesMutator().addCacheListener(new ClientListener());
        return null;
      }
test has a client, two accessors and a datastore pool connects to two accessors. we then close
the server in first accessor and verify failover
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ClientServerTransactionDUnitTest.java