@Test
  public void testInstantiatorCount() throws Exception {
    PORT1 = initServerCache(server1);
    PORT2 = initServerCache(server2);

    client1.invoke(() -> InstantiatorPropagationDUnitTest
        .createClientCache(NetworkUtils.getServerHostName(server1.getHost()), PORT1));
    client2.invoke(() -> InstantiatorPropagationDUnitTest
        .createClientCache(NetworkUtils.getServerHostName(server1.getHost()), PORT1));
    createClientCache(NetworkUtils.getServerHostName(server2.getHost()), PORT2);
    unregisterInstantiatorsInAllVMs();

    // wait for client2 to come online
    Wait.pause(2000);

    client1.invoke(InstantiatorPropagationDUnitTest::registerTestObject12);
    Wait.pause(4000);

    client1.invoke(() -> InstantiatorPropagationDUnitTest.verifyInstantiators(1));

    server1.invoke(() -> InstantiatorPropagationDUnitTest.verifyInstantiators(1));

    server2.invoke(() -> InstantiatorPropagationDUnitTest.verifyInstantiators(1));

    client2.invoke(() -> InstantiatorPropagationDUnitTest.verifyInstantiators(1));

    verifyInstantiators(1);

    unregisterInstantiatorsInAllVMs();
  }
In this test there are 2 clients connected to 1 server and 1 client connected to the other
server.Registered one instantiator on one client(client1). Verified, if that instantiator gets
propagated to the server the client is connected to(server1), to client2, to the other
server(server2) in the DS and the client that is connected to server2.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/tier/sockets/InstantiatorPropagationDUnitTest.java