private static Properties defaultProperties() {
    Properties props = new Properties();
    int[] ports = getRandomAvailableTCPPorts(2);
    props.setProperty(HTTP_SERVICE_PORT, String.valueOf(ports[0]));
    props.setProperty(JMX_MANAGER_PORT, String.valueOf(ports[1]));
    return props;
  }
By default, assign available HTTP and JMX ports.
geode-dunit/src/main/java/org/apache/geode/test/junit/rules/LocatorLauncherStartupRule.java