@Override
        public void onEvent(CqEvent cqEvent) {
          Object key = cqEvent.getKey();
          if (LAST_KEY.equals(key)) {
            lastKeyReceived = true;
          }
          logger.fine(
              "CQ event received for (key, value): (" + key + ", " + cqEvent.getNewValue() + ")");
        }
This test does the following for single key (<b> full cycle</b>):<br>
1)Verifies that client-server, peer-peer and server-client processing delta<br>
geode-cq/src/distributedTest/java/org/apache/geode/internal/cache/tier/sockets/ClientToServerDeltaDUnitTest.java