map.put(FieldNames.DOC_FREQ, docFreq);
        map.put(FieldNames.USER_BOOST, userBoost);
        map.put(FieldNames.SCORE, (queryFreq + docFreq) * userBoost);
        map.put(FieldNames.TIMESTAMP, timestamp.toInstant().toEpochMilli());
        return map;
    }

    /**
     * Parses a source map and returns a SuggestItem instance.
     * @param source The source map.
     * @return A SuggestItem instance.
     */

            return Long.toString(date.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
        } else if (format.contains("date_optional_time")) {
            return DateTimeFormatter.ISO_DATE_TIME.format(date);
        } else {
            return Long.toString(date.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
        }
    }

        final BoolQueryBuilder boolQueryBuilder = QueryBuilders.boolQuery();
        boolQueryBuilder
                .must(QueryBuilders.rangeQuery(FieldNames.TIMESTAMP).lt(time.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli()));

        boolQueryBuilder.must(QueryBuilders.termQuery(FieldNames.KINDS, SuggestItem.Kind.DOCUMENT.toString()));

            return Long.toString(date.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
        } else if (format.contains("date_optional_time")) {
            return DateTimeFormatter.ISO_DATE_TIME.format(date);
        } else {
            return Long.toString(date.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
        }
    }

            return Long.toString(date.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
        } else if (format.contains("date_optional_time")) {
            return DateTimeFormatter.ISO_DATE_TIME.format(date);
        } else {
            return Long.toString(date.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli());
        }
    }

    public SuggestDeleteResponse deleteOldWords(final ZonedDateTime threshold) {
        final long start = System.currentTimeMillis();
        final String query = FieldNames.TIMESTAMP + ":[* TO " + threshold.toInstant().toEpochMilli() + "] NOT " + FieldNames.KINDS + ':'
                + SuggestItem.Kind.USER;
        deleteByQuery(query);
        return new SuggestDeleteResponse(null, System.currentTimeMillis() - start);
    }

    /**