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`)
4. Applies language-specific analyzers for better search results

Configured in `fess_config.properties`:
```properties
indexer.language.fields=content,important_content,title
```

            rcae.setLogLevel(CrawlingAccessException.WARN);
            throw rcae;
        }
        if (content == null) {
            content = StringUtil.EMPTY;
        }
        final String contentMeta = contentMetaBuf.toString().trim();

        final CrawlingInfoHelper crawlingInfoHelper = ComponentUtil.getCrawlingInfoHelper();