* Contains helper methods for string operations, including backported JDK functionality
 * for compatibility with older Java versions.
 */
public final class StringUtil {

    /**
     *
     */
    private StringUtil() {
    }

    /**
     * Implementation of {@link java.lang.String#join} backported for JDK7.
     *
     * @param delimiter the separator to use between elements

     * <p>
     * Usage example:
     * </p>
     *
     * <pre>
     * StringUtil.defaultString(null, "NULL")  = "NULL"
     * StringUtil.defaultString("", "NULL")    = ""
     * StringUtil.defaultString("aaa", "NULL") = "aaa"
     * StringUtil.defaultString("aaa", null)   = "aaa"
     * StringUtil.defaultString(null, null)    = null
     * </pre>
     *
     * @param str

            if (StringUtil.isBlank(value)) {
                map = Collections.emptyMap();
            } else {
                final Set<String> keySet = new HashSet<>();
                map = split(value, "\n").get(stream -> stream.filter(StringUtil::isNotBlank).map(s -> {
                    final String[] pair = s.split("=");
                    if (pair.length == 1) {
                        return new Pair<>(StringUtil.EMPTY, pair[0].trim());

        // Add defensive null/blank checks
        if (StringUtil.isBlank(username) || StringUtil.isBlank(password)) {
            if (logger.isDebugEnabled()) {
                logger.debug("Login failed: username or password is blank");
            }
            return OptionalEntity.empty();
        }

        if (StringUtil.isBlank(fessConfig.getLdapProviderUrl()) || !validate()) {

                            .filter(StringUtil::isNotBlank)
                            .distinct()
                            .collect(Collectors.joining("\n")));
                    form.virtualHosts = stream(entity.getVirtualHosts())
                            .get(stream -> stream.filter(StringUtil::isNotBlank).map(String::trim).collect(Collectors.joining("\n")));

            final String includedUrlsStr = webConfig.getIncludedUrls() != null ? webConfig.getIncludedUrls() : StringUtil.EMPTY;
            final String excludedUrlsStr = webConfig.getExcludedUrls() != null ? webConfig.getExcludedUrls() : StringUtil.EMPTY;

            // num of threads
            final CrawlerContext crawlerContext = crawler.getCrawlerContext();
            final int numOfThread =

        final String value = ComponentUtil.getFessConfig().getSystemProperty("oic.default.groups");
        if (StringUtil.isBlank(value)) {
            return StringUtil.EMPTY_STRINGS;
        }
        return split(value, ",").get(stream -> stream.filter(StringUtil::isNotBlank).map(String::trim).toArray(n -> new String[n]));
    }

    /**
     * Gets the default roles as an array.
     *

        final String slackWebhookUrls = fessConfig.getSlackWebhookUrls();
        if (StringUtil.isBlank(slackWebhookUrls)) {
            return;
        }
        final String body = toSlackMessage(discloser);
        StreamUtil.split(slackWebhookUrls, "[,\\s]").of(stream -> stream.filter(StringUtil::isNotBlank).forEach(url -> {

                .of(stream -> stream.filter(StringUtil::isNotBlank).forEach(contentFieldNameSet::add));
        split(fessConfig.getSuggestFieldTags(), ",").of(stream -> stream.filter(StringUtil::isNotBlank).forEach(tagFieldNameSet::add));
        split(fessConfig.getSuggestFieldRoles(), ",").of(stream -> stream.filter(StringUtil::isNotBlank).forEach(roleFieldNameSet::add));

                            .filter(StringUtil::isNotBlank)
                            .distinct()
                            .collect(Collectors.joining("\n")));
                    form.virtualHosts = stream(entity.getVirtualHosts())
                            .get(stream -> stream.filter(StringUtil::isNotBlank).map(String::trim).collect(Collectors.joining("\n")));