* <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

     * @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) {

                return pagingQueryList.stream()
                        .filter(s -> prefix == null || !s.startsWith(prefix))
                        .collect(Collectors.joining("&", "&", StringUtil.EMPTY));
            }
            return null;
        }).orElse(StringUtil.EMPTY);
    }

    /**
     * Generates URL query parameters for facet filtering.
     *
     * @return URL-encoded query string containing facet parameters

     */
    public static String getAppType() {
        final String appType = System.getenv(FESS_APP_TYPE);
        if (StringUtil.isNotBlank(appType)) {
            return appType;
        }
        return StringUtil.EMPTY;
    }

    /**
     * Gets the override configuration path from environment variable when running in Docker.

                            .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")));

            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;
    }

        putResultDataBody(dataMap, fessConfig.getIndexFieldVirtualHost(),
                stream(crawlingConfig.getVirtualHosts()).get(stream -> stream.filter(StringUtil::isNotBlank).collect(Collectors.toList())));
        // TODO date
        // lang
        if (StringUtil.isNotBlank(fessConfig.getCrawlerDocumentFileDefaultLang())) {

                .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));

                    postcard.setCrawlerExecTime(getValueFromMap(dataMap, "crawlerExecTime", "0"));
                    postcard.setCrawlerStartTime(getValueFromMap(dataMap, "crawlerStartTime", StringUtil.EMPTY));
                    postcard.setDataCrawlEndTime(getValueFromMap(dataMap, "dataCrawlEndTime", StringUtil.EMPTY));

            }

            userCode = getUserCodeFromCookie(request);
            if (StringUtil.isBlank(userCode)) {
                userCode = getUserCodeFromUserBean(request);
                if (StringUtil.isBlank(userCode)) {
                    userCode = getId();
                }
            }

            if (StringUtil.isNotBlank(userCode)) {
                updateUserSessionId(userCode);
            }