@Override
  public Properties getDistributedSystemProperties() {
    Properties config = new Properties();
    config.setProperty(MCAST_PORT, "0");
    return config;
  }
Verifies that overriding {@code getDistributedSystemProperties} results in
{@code disconnectAllFromDS} during tear down.
geode-dunit/src/distributedTest/java/org/apache/geode/test/dunit/tests/OverridingGetPropertiesDisconnectsAllDistributedTest.java