@Override
  public void addGatewayReceiver(GatewayReceiver receiver) {
    throwIfClient();
    stopper.checkCancelInProgress(null);
    requireNonNull(receiver, "GatewayReceiver must be supplied.");
    gatewayReceiver.set(receiver);
  }
For use by unit tests to inject a mocked ccpTimer
geode-core/src/main/java/org/apache/geode/internal/cache/GemFireCacheImpl.java