return null;
        }

        final Set<RequestData> childUrlSet = new LinkedHashSet<>();
        for (final String anchor : anchorList) {
            childUrlSet.add(RequestDataBuilder.newRequestData().get().url(anchor).build());
        }
        return childUrlSet;
    }

    protected Set<RequestData> getChildUrlSet(final SearchEngineClient searchEngineClient, final String id) {