private AcceptorImpl getAcceptorImpl(CacheServerImpl server) {
    try {
      Method getAcceptor = server.getClass().getMethod("getAcceptor");
      return (AcceptorImpl) getAcceptor.invoke(server);
    } catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException e) {
      throw new RuntimeException(e);
    }
  }
Get the port that the standard dunit locator is listening on.
geode-core/src/upgradeTest/java/org/apache/geode/internal/cache/rollingupgrade/RollingUpgrade2DUnitTestBase.java