private int createFirstRemoteLocator(int systemId, int remoteLocatorPort) {
    stopOldLocator();
    int locatorPort = getRandomAvailableTCPPort();
    startLocator(systemId, locatorPort, locatorPort, remoteLocatorPort, true);
    return locatorPort;
  }
Since the sender is attached to a region and in use, it can not be destroyed. Hence, exception
is thrown by the sender API.
geode-wan/src/distributedTest/java/org/apache/geode/internal/cache/wan/serial/SerialGatewaySenderOperationsDistributedTest.java