private void validateServerClientRegionEntries(VM server, VM client, final String regionName) {

    server.invoke(new CacheSerializableRunnable("Server Region Entries") {
      @Override
      public void run2() throws CacheException {
        Region region = getRootRegion().getSubregion(regionName);
        logger.info("### Entries in Server :" + region.keySet().size());
      }
    });

    client.invoke(new CacheSerializableRunnable("Client Region Entries") {
      @Override
      public void run2() throws CacheException {
        Region region = getRootRegion().getSubregion(regionName);
        logger.info("### Entries in Client :" + region.keySet().size());
      }
    });
  }
Tests execution of queries with NULL in where clause like where ID = NULL etc.
geode-cq/src/distributedTest/java/org/apache/geode/cache/query/cq/dunit/CqQueryDUnitTest.java