@Override
    public Object call() throws Exception {
      RegionFactory rf = getCache().createRegionFactory(RegionShortcut.REPLICATE);
      rf.setConcurrencyChecksEnabled(getConcurrencyChecksEnabled());
      rf.create(regionName);
      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