class HostInterceptor implements Interceptor {

  @Override
  public Event intercept(Event event) {
    Map<String, String> headers = event.getHeaders();

    if (preserveExisting && headers.containsKey(header)) {
      return event;
    }
    if (host != null) {
      headers.put(header, host);
    }

    return event;
  }

  private  HostInterceptor(boolean preserveExisting,
      boolean useIP, String header);

}