* <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

 * 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

            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());

import org.junit.jupiter.params.provider.ValueSource;

/**
 * Test class for StringUtil utility methods
 */
class StringUtilTest {

    @Test
    @DisplayName("Should join single element without delimiter")
    void testJoinSingleElement() {
        String result = StringUtil.join(",", "hello");
        assertEquals("hello", result);
    }

    @Test

        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 -> {

     * @return the host name, or empty string if URL is blank, or unknown hostname if parsing fails
     */
    default String getHost(final String u) {
        if (StringUtil.isBlank(u)) {
            return StringUtil.EMPTY; // empty
        }

        String url = u;
        final String originalUrl = url;

        int idx = url.indexOf("://");
        if (idx >= 0) {

        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.
     *

                .ifPresent(s -> entry.put(new BasicAttribute(fessConfig.getLdapAttrTelephoneNumber(), s)));
        OptionalUtil.ofNullable(user.getHomePhone())
                .filter(StringUtil::isNotBlank)
                .ifPresent(s -> entry.put(new BasicAttribute(fessConfig.getLdapAttrHomePhone(), s)));
        OptionalUtil.ofNullable(user.getHomePostalAddress())
                .filter(StringUtil::isNotBlank)

        final String tokenPattern = getParameter(TOKEN_PATTERN);
        final List<Pair<String, String>> responseParams = new ArrayList<>();
        final String encoding = getParameter(ENCODING);
        if (StringUtil.isNotBlank(tokenUrl) && StringUtil.isNotBlank(tokenPattern)) {
            final String tokenHttpMethod = getParameter(TOKEN_METHOD);
            final String tokenReqParams = getParameter(TOKEN_PARAMTERS);

            credentials = new NTCredentials(username, password == null ? StringUtil.EMPTY : password,
                    workstation == null ? StringUtil.EMPTY : workstation, domain == null ? StringUtil.EMPTY : domain);
        } else {
            credentials = new UsernamePasswordCredentials(username, password == null ? StringUtil.EMPTY : password);
        }
        return credentials;
    }