@Override
  public final void preTearDown() throws Exception {
    // reset all flags
    DeltaTestImpl.resetDeltaInvokationCounters();
    server.invoke(DeltaTestImpl::resetDeltaInvokationCounters);
    server2.invoke(DeltaTestImpl::resetDeltaInvokationCounters);
    client.invoke(DeltaTestImpl::resetDeltaInvokationCounters);
    client2.invoke(DeltaTestImpl::resetDeltaInvokationCounters);
    // close the clients first
    client.invoke(ClientToServerDeltaDUnitTest::closeCache);
    client2.invoke(ClientToServerDeltaDUnitTest::closeCache);
    // then close the servers
    server.invoke(ClientToServerDeltaDUnitTest::closeCache);
    server2.invoke(ClientToServerDeltaDUnitTest::closeCache);
  }
Test client to server flow for delta propogation

@since GemFire 6.1
geode-cq/src/distributedTest/java/org/apache/geode/internal/cache/tier/sockets/ClientToServerDeltaDUnitTest.java