if (queries != null && queries.length > 0) {
                doc.put(HL_CACHE, replaceHighlightQueries(cache, queries));
            } else {
                doc.put(HL_CACHE, cache);
            }
        } else {
            doc.put(fessConfig.getIndexFieldCache(), StringUtil.EMPTY);
            doc.put(HL_CACHE, StringUtil.EMPTY);
        }

        try {

# Field name for primary term in the index.
index.field.primary_term=_primary_term
# Field name for language in the index.
index.field.lang=lang
# Field name for cache status in the index.
index.field.has_cache=has_cache
# Field name for last modified date in the index.
index.field.last_modified=last_modified
# Field name for anchor in the index.
index.field.anchor=anchor
# Field name for segment in the index.

    /** The key of the configuration. e.g. lang */
    String INDEX_FIELD_LANG = "index.field.lang";

    /** The key of the configuration. e.g. has_cache */
    String INDEX_FIELD_has_cache = "index.field.has_cache";

    /** The key of the configuration. e.g. last_modified */
    String INDEX_FIELD_last_modified = "index.field.last_modified";

    /** The key of the configuration. e.g. anchor */