@Override
  public Set<FaultDomain> getFaultDomainsForHost(String host) {
    return Collections.singleton(SINGLE_FAULT_DOMAIN);
  }
Simple placeholder implementation of {@link FaultDomainManager} which contains a single fault domain for all hosts.
This can be used when another concrete {@link FaultDomainManager} is undesirable or unavailable, but features which
depend on a {@link FaultDomainManager} (such as standby containers) may have unexpected behavior.
samza-core/src/main/java/org/apache/samza/clustermanager/SingleFaultDomainManager.java