"ctx._source." + fessConfig.getIndexFieldClickCount() + "+=" + count.toString());
                                        final Map<String, Object> upsertMap = new HashMap<>();
                                        upsertMap.put(fessConfig.getIndexFieldClickCount(), count);

     * comment: Field name for click count in the index.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getIndexFieldClickCount();

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