private static void setClientServerObserver1() {
    PoolImpl.IS_INSTANTIATOR_CALLBACK = true;
    ClientServerObserverHolder.setInstance(new ClientServerObserverAdapter() {
      @Override
      public void beforeSendingToServer(EventID eventID) {
        eventId = eventID;
      }
    });
  }
Register two DataSerializers on the server and verify that they get propagated to client.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/tier/sockets/DataSerializerPropagationDUnitTest.java