assertThat(response.trailers()).isEmpty()
  }

  @Test
  fun worksIfTrailersSet() {
    val response =
      newResponse("".toResponseBody()) {
        trailers(
          object : TrailersSource {
            override fun get() = Headers.headersOf("a", "b")
          },
        )
      }

    assertThat(response.trailers()["a"]).isEqualTo("b")
  }

    var trailers: Headers = mockResponse.trailers
    mockResponse = mockResponse.clearHeaders()
    mockResponse = mockResponse.addHeader("")
    mockResponse = mockResponse.addHeader("", "")
    mockResponse = mockResponse.addHeaderLenient("", Any())
    mockResponse = mockResponse.setHeader("", Any())
    mockResponse.headers = headersOf()
    mockResponse.trailers = headersOf()

});

Crawler crawler = container.getComponent("crawler");
crawler.addUrl("https://example.com");
crawler.crawlerContext.setMaxAccessCount(500);
String sessionId = crawler.execute();
```

### Background Crawling

```java
// Configure for background execution
crawler.setBackground(true);
String sessionId = crawler.execute();

// Check crawling status

import org.codelibs.fess.crawler.filter.impl.UrlFilterImpl;
import org.codelibs.fess.crawler.service.DataService;
import org.codelibs.fess.crawler.service.UrlFilterService;
import org.codelibs.fess.crawler.service.UrlQueueService;
import org.codelibs.fess.crawler.transformer.impl.FileTransformer;
import org.codelibs.fess.crawler.util.CrawlerWebServer;
import org.codelibs.opensearch.runner.OpenSearchRunner;
import org.dbflute.utflute.lastadi.LastaDiTestCase;

**DI Config**: `fess-crawler-lasta/src/main/resources/`
- `crawler.xml` (root), `crawler/client.xml`, `crawler/extractor.xml`, `crawler/rule.xml`, `crawler/transformer.xml`, `crawler/transformer_basic.xml`
- `crawler/mimetype.xml`, `crawler/encoding.xml`, `crawler/robotstxt.xml`, `crawler/sitemaps.xml`

{"index":{"_index":"fess_config.scheduled_job","_id":"default_crawler"}}
{"name":"Default Crawler","target":"all","cronExpression":"0 0 * * *","scriptType":"groovy","scriptData":"return container.getComponent(\"crawlJob\").logLevel(\"info\").gcLogging().execute(executor);","jobLogging":true,"crawler":true,"available":true,"sortOrder":1,"createdBy":"system","createdTime":0,"updatedBy":"system","updatedTime":0}
{"index":{"_index":"fess_config.scheduled_job","_id":"suggest_indexer"}}

<!DOCTYPE components PUBLIC "-//DBFLUTE//DTD LastaDi 1.0//EN"
	"http://dbflute.org/meta/lastadi10.dtd">
<components namespace="fessCrawler">
	<include path="crawler/container.xml" />
	<include path="crawler/transformer.xml" />

	<component name="ruleManager" class="org.codelibs.fess.crawler.rule.impl.RuleManagerImpl" instance="prototype">
		<postConstruct name="addRule">
			<arg>sitemapsRule</arg>
		</postConstruct>
		<postConstruct name="addRule">

    val request =
      Request
        .Builder()
        .url("http://square.com/")
        .header("TE", "trailers")
        .build()
    val expected =
      headerEntries(
        ":method",
        "GET",
        ":path",
        "/",
        ":scheme",
        "http",
        "te",
        "trailers",
      )
    assertThat(http2HeadersList(request)).isEqualTo(expected)
  }

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.crawler.container;

import org.codelibs.fess.crawler.Crawler;
import org.codelibs.fess.crawler.helper.MemoryDataHelper;
import org.codelibs.fess.crawler.service.DataService;
import org.codelibs.fess.crawler.service.UrlQueueService;
import org.dbflute.utflute.lastadi.LastaDiTestCase;
import org.junit.jupiter.api.Test;

		return errServerNotInitialized
	}

	started := tracker.Started
	if started.IsZero() || started.Equal(timeSentinel) {
		healingLogIf(ctx, fmt.Errorf("unexpected tracker healing start time found: %v", started))
		started = time.Time{}
	}

	// Final tracer update before quitting
	defer func() {
		tracker.setObject("")
		tracker.setBucket("")
		healingLogIf(ctx, tracker.update(ctx))
	}()