@Override
  public final void preTearDown() throws Exception {
    // close client
    client1.invoke(EventIdOptimizationDUnitTest::closeCache);
    client2.invoke(EventIdOptimizationDUnitTest::closeCache);
    // close server
    server1.invoke(EventIdOptimizationDUnitTest::closeCache);
    server2.invoke(EventIdOptimizationDUnitTest::closeCache);
  }
Closes the caches on clients and servers
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ha/EventIdOptimizationDUnitTest.java