@VisibleForTesting
  long putSubject(Subject subject, long existingUniqueId) {
    final long uniqueId = clientUserAuths.putSubject(subject, existingUniqueId);
    // also update the subject in the CacheClientProxy if it's in single user mode
    CacheClientProxy clientProxy =
        getAcceptor().getCacheClientNotifier().getClientProxy(getProxyID());
    // update the subject (in single user mode) in clientProxy if exists
    if (clientProxy != null && clientProxy.getSubject() != null
        && clientProxy.isWaitingForReAuthentication()) {
      secureLogger.debug("update subject on client proxy {} with uniqueId {}", clientProxy,
          uniqueId);
      clientProxy.setSubject(subject);
      clientProxy.notifyReAuthentication();
    }
    return uniqueId;
  }
@return whether this is a connection to a client, regardless of protocol.
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/ServerConnection.java