private static void verifyCacheClientProxyOnServer() {
    Cache cache = new ClientServerMiscDUnitTestBase().getCache();
    assertEquals("More than one BridgeServer", 1, cache.getCacheServers().size());
    CacheServerImpl bs = (CacheServerImpl) cache.getCacheServers().iterator().next();
    assertNotNull(bs);
    assertNotNull(bs.getAcceptor());
    final CacheClientNotifier ccn = bs.getAcceptor().getCacheClientNotifier();

    assertNotNull(ccn);

    await()
        .until(() -> ccn.getClientProxies().size() == 1);
  }
bug 35380: Cycling a DistributedSystem with an initialized pool causes interest registration
NPE

Test Scenario:

Create a DistributedSystem (DS1). Create a pool, initialize (creates a proxy with DS1 memberid)
Disconnect DS1. Create a DistributedSystem (DS2). Create a Region with pool, it attempts to
register interest using DS2 memberid, gets NPE.
geode-dunit/src/main/java/org/apache/geode/internal/cache/tier/sockets/ClientServerMiscDUnitTestBase.java