@Override
  public boolean isDurableClient() {
    DistributionConfig config = distributedSystem.getConfig();
    String durableClientId = config.getDurableClientId();
    return durableClientId != null && durableClientId.length() > 0;
  }
Test hook used to simulate a kill of the primaryEndpoint
geode-core/src/main/java/org/apache/geode/cache/client/internal/PoolImpl.java