@Override
  public final void preTearDown() throws Exception {
    client1.invoke(HAClearDistributedTest::closeCache);
    client2.invoke(HAClearDistributedTest::closeCache);
    server1.invoke(HAClearDistributedTest::closeCache);
    server2.invoke(HAClearDistributedTest::closeCache);
    closeCache();
  }
This is the Dunit test to verify clear and destroyRegion operation in Client-Server
configuration.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ha/HAClearDistributedTest.java