List<SuggestItem> parseQueryLog(QueryLog queryLog, String[] fields, String[] tagFieldNames, String roleFieldName,
            ReadingConverter readingConverter, Normalizer normalizer);

    List<SuggestItem> parseDocument(Map<String, Object> document, String[] fields, String[] tagFieldNames, String roleFieldName,
            String langFieldName, ReadingConverter readingConverter, ReadingConverter contentsReadingConverter, Normalizer normalizer,

            throw new SuggesterException("Failed to create SuggestItem from queryLog.", e);
        }

        return items;
    }

    @Override
    public List<SuggestItem> parseDocument(final Map<String, Object> document, final String[] fields, final String[] tagFieldNames,
            final String roleFieldName, final String langFieldName, final ReadingConverter readingConverter,

            if (parallel) {
                stream.parallel();
            }
            final SuggestItem[] items = stream.flatMap(document -> {
                try {
                    return contentsParser.parseDocument(document, supportedFields, tagFieldNames, roleFieldName, langFieldName,
                            readingConverter, contentsReadingConverter, normalizer, analyzer).stream();