2. **Browser header**: `Accept-Language` header
3. **Fallback**: English (from `fess_label.properties` and `fess_message.properties`)

### Document Language Detection

During crawling and indexing, Fess:

1. Detects language from document content using Apache Tika
2. Validates against `supported.languages` list
3. Creates language-specific fields (e.g., `content_ja`, `title_en`, `content_sv`)

import org.codelibs.fess.app.web.base.login.FessLoginAssist.LoginCredentialResolver;
import org.codelibs.fess.app.web.base.login.SamlCredential;
import org.codelibs.fess.app.web.base.login.SamlCredential.SamlUser;
import org.codelibs.fess.crawler.Constants;
import org.codelibs.fess.exception.SsoLoginException;
import org.codelibs.fess.exception.SsoMessageException;
import org.codelibs.fess.exception.SsoProcessException;

<div class="wrapper">
    <jsp:include page="/WEB-INF/view/common/admin/header.jsp"></jsp:include>
    <jsp:include page="/WEB-INF/view/common/admin/sidebar.jsp">
        <jsp:param name="menuCategoryType" value="crawl"/>
        <jsp:param name="menuType" value="fileConfig"/>
    </jsp:include>
    <main class="content-wrapper">
        <div class="content-header">
            <div class="container-fluid">

     * Test if a method is a prime declaration or an overrides that change the signature.
     *
     * There's no way to tell from the byte code that a method overrides the signature
     * of a parent declaration other than crawling up the type hierarchy.
     */
    private
    fun isSignificantDeclaration(methodNode: MethodNode): Boolean {

        if (methodNode.access.isSynthetic) return false

        if (!hasSuperType) return true

    @Resource
    private RequestHeaderService requestHeaderService;
    @Resource
    private ReqHeaderPager reqHeaderPager;
    /** Web configuration service for managing web crawl configurations. */
    @Resource
    protected WebConfigService webConfigService;

    // ===================================================================================

                                            </div>
                                        </div>
                                    </div>
                                </div>
                                    <%-- Crawler --%>
                                <h4><la:message key="labels.general_menu_crawler"/></h4>
                                <div class="form-group row">

import org.codelibs.core.lang.StringUtil;
import org.codelibs.core.lang.ThreadUtil;
import org.codelibs.core.misc.Pair;
import org.codelibs.fess.Constants;
import org.codelibs.fess.crawler.util.CharUtil;
import org.codelibs.fess.exception.FessSystemException;
import org.codelibs.fess.mylasta.action.FessMessages;
import org.codelibs.fess.mylasta.action.FessUserBean;

labels.protwordsFile=Protwordsファイル
labels.kuromojiFile=Kuromojiファイル
labels.elevateWordFile=追加ワードファイル
labels.badWordFile=除外ワードファイル
labels.urlExpr=条件
labels.boostExpr=ブースト値式
labels.confirmPassword=確認
labels.crawler=クローラー
labels.crudMode=モード
labels.errorCountMax=最大エラー数
labels.errorCountMin=最小エラー数
labels.facet=ファセット
labels.geo=ジオ
labels.groups=グループ
labels.hash=ハッシュ
labels.maxSize=最大サイズ
labels.order=順番

 * shared state without additional synchronization necessary for visibility to later executions of
 * the life cycle methods.
 *
 * <h3>Usage Example</h3>
 *
 * <p>Here is a sketch of a service which crawls a website and uses the scheduling capabilities to
 * rate limit itself.
 *
 * {@snippet :
 * class CrawlingService extends AbstractScheduledService {
 *   private Set<Uri> visited;
 *   private Queue<Uri> toCrawl;

 * shared state without additional synchronization necessary for visibility to later executions of
 * the life cycle methods.
 *
 * <h3>Usage Example</h3>
 *
 * <p>Here is a sketch of a service which crawls a website and uses the scheduling capabilities to
 * rate limit itself.
 *
 * {@snippet :
 * class CrawlingService extends AbstractScheduledService {
 *   private Set<Uri> visited;
 *   private Queue<Uri> toCrawl;