docId = null;
            }
            if (StringUtil.isNotBlank(docId)) {
                return searchEngineClient.getDocument(fessConfig.getIndexDocumentUpdateIndex(), builder -> {
                    builder.setQuery(QueryBuilders.termQuery(fessConfig.getIndexFieldDocId(), docId));
                    return true;
                });
            }
            break;
        default:
            break;

import java.util.ConcurrentModificationException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.jspecify.annotations.Nullable;

/**
 * A builder of {@link ConcurrentMap} instances that can have keys or values automatically wrapped
 * in {@linkplain WeakReference weak} references.
 *
 * <p>Usage example:
 *
 * {@snippet :

    ) {
      val url = "http://example.com/websocket"
      val response =
        Response
          .Builder()
          .code(101)
          .message("OK")
          .request(Request.Builder().url(url).build())
          .headers(responseHeaders!!)
          .protocol(Protocol.HTTP_1_1)
          .build()
      webSocket =
        RealWebSocket(

    ImmutableSet.Builder<String> builder = ImmutableSet.builder();
    Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
    assertTrue(interfaces.hasMoreElements());
    while (interfaces.hasMoreElements()) {
      NetworkInterface i = interfaces.nextElement();
      builder.add(i.getName()).add(String.valueOf(i.getIndex()));
    }

      int end,
      char replacement,
      StringBuilder builder,
      boolean inMatchingGroup) {
    for (int i = start; i < end; i++) {
      char c = sequence.charAt(i);
      if (matches(c)) {
        if (!inMatchingGroup) {
          builder.append(replacement);
          inMatchingGroup = true;
        }
      } else {
        builder.append(c);
        inMatchingGroup = false;
      }
    }

			EnvMap:   c.getTargetEnvs(subSys, target, defKVS, redactSecrets),
		})
	}

	return r, nil
}

// AddEnvString adds env vars to the given string builder.
func (cs *SubsysInfo) AddEnvString(b *strings.Builder) {
	for _, v := range cs.Defaults {
		if ep, ok := cs.EnvMap[v.Key]; ok {
			b.WriteString(KvComment)
			b.WriteString(KvSpaceSeparator)
			b.WriteString(ep.Name)

| `LanguageHelper` | `org.codelibs.fess.helper` | Language detection and validation |
| `SystemHelper` | `org.codelibs.fess.helper` | UI language dropdown builder |
| `FessUserLocaleProcessProvider` | `org.codelibs.fess.mylasta.direction.sponsor` | User locale detection |

## Language Detection and Selection

### User Interface Language

### Key Architectural Patterns
- **Factory Pattern** - `BeanDescFactory` for creating bean descriptors, `ParameterizedClassDescFactory` for generic type handling
- **Builder Pattern** - `CopyOptions` for configuring bean copying operations with fluent API
- **Adapter Pattern** - Logging adapters (`JclLoggerAdapter`, `JulLoggerAdapter`) for different logging frameworks

        if (robotsTxtHelper != null) {
            robotsTxtHelper.setEnabled(robotsTxtEnabled);
        }

        // httpclient
        final RequestConfig.Builder requestConfigBuilder = RequestConfig.custom();
        final HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();

        List<String> words = Collections.emptyList();
        QueryBuilder result = request.buildFilterQuery("tags", words);
        assertNotNull(result);
        // Empty list should still return a valid query builder
        assertTrue(result instanceof BoolQueryBuilder);
    }

    @Test
    public void test_buildFilterQuery_differentFields() {