}

            @Override
            public String getIndexAdminDoubleFields() {
                return "";
            }

            @Override
            public String getIndexFieldId() {
                return "_id";
            }

            @Override
            public String getIndexFieldVersion() {
                return "_version";
            }

            @Override

                final String newId = ComponentUtil.getCrawlingInfoHelper().generateId(entity);
                final String oldId = (String) entity.get(fessConfig.getIndexFieldId());
                if (!newId.equals(oldId)) {
                    entity.put(fessConfig.getIndexFieldId(), newId);
                    entity.remove(fessConfig.getIndexFieldVersion());

        SearchResponse response = client.prepareSearch(index)
                .setScroll(scrollForDelete)
                .setSize(sizeForDelete)
                .setFetchSource(new String[] { fessConfig.getIndexFieldId() }, null)
                .setQuery(queryBuilder)
                .setPreference(Constants.SEARCH_PREFERENCE_LOCAL)
                .execute()
                .actionGet(fessConfig.getIndexScrollSearchTimeout());

                                .stream()
                                .map(doc -> {
                                    final String id = DocumentUtil.getValue(doc, fessConfig.getIndexFieldId(), String.class);
                                    final String docId = DocumentUtil.getValue(doc, fessConfig.getIndexFieldDocId(), String.class);

                        }

                        final String id = DocumentUtil.getValue(doc, fessConfig.getIndexFieldId(), String.class);
                        searchHelper.update(id, builder -> {
                            final Script script = ComponentUtil.getLanguageHelper()

     * The value is, e.g. _id <br>
     * comment: Field name for internal ID in the index.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getIndexFieldId();

    /**
     * Get the value for the key 'index.field.version'. <br>
     * The value is, e.g. _version <br>
     * comment: Field name for version in the index.