private boolean isTimedOut(ClientProxyMembershipID client) {
    return timedOutDurableClientProxies.contains(client);
  }
Removes an existing {@code CacheClientProxy} from the list of known client proxies

@param proxy The {@code CacheClientProxy} to remove
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/CacheClientNotifier.java