@Override
    public void run2() {
      if (pool.getCancelCriterion().isCancelInProgress()) {
        return;
      }
      LocatorListResponse response = (LocatorListResponse) queryLocators(LOCATOR_LIST_REQUEST);
      updateLocatorList(response);
    }
This method will add bad locator only when locator with hostname and port is not already in
list.
geode-core/src/main/java/org/apache/geode/cache/client/internal/AutoConnectionSourceImpl.java