* @param sources the source documents
     * @return the source titles suffix, or empty string
     */
    private String buildSourceTitlesSuffix(final List<ChatSource> sources) {
        return buildSourceTitlesSuffix(sources, Integer.MAX_VALUE);
    }

    private String buildSourceTitlesSuffix(final List<ChatSource> sources, final int maxSuffixLength) {
        if (sources == null || sources.isEmpty()) {
            return "";