Function<? super T, ? extends K> keyFunction,
          Function<? super T, ? extends V> valueFunction) {
    return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
  }

  // Casting to any type is safe because the set will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableBiMap<K, V> of() {
    return (ImmutableBiMap<K, V>) RegularImmutableBiMap.EMPTY;
  }

                }
                default -> null;
                };
            });
        } catch (final Exception e) {
            logger.warn("Failed to access a crawling config cache: {}", configId, e);
            return null;
        }
    }

    public OptionalThing<String> getPipeline(final String configId) {
        final CrawlingConfig config = getCrawlingConfig(configId);

    fun isCacheable(
      response: Response,
      request: Request,
    ): Boolean {
      // Always go to network for uncacheable response codes (RFC 7231 section 6.1), This
      // implementation doesn't support caching partial content.
      when (response.code) {
        HTTP_OK,
        HTTP_NOT_AUTHORITATIVE,
        HTTP_NO_CONTENT,
        HTTP_MULT_CHOICE,
        HTTP_MOVED_PERM,
        HTTP_NOT_FOUND,

        if (configList.isEmpty()) {
            // nothing
            if (logger.isInfoEnabled()) {
                logger.info("No crawling target data.");
            }
            return;
        }

        doCrawl(sessionId, configList);
    }

    public void crawl(final String sessionId, final List<String> configIdList) {

    /*
     * This test will catch problems where the underlying iterator
     * throws a RuntimeException when retrieving the nth element.
     *
     * If the PeekingIterator is caching elements too aggressively,
     * it may throw the exception on the (n-1)th element (oops!).
     */

    /* Checks the case where the first element throws an exception. */

    List<Integer> list = emptyList();

  }

  /**
   * Provides a check of whether an exception type is valid for use with {@link
   * FuturesGetChecked#getChecked(Future, Class)}, possibly using caching.
   *
   * <p>Uses reflection to gracefully fall back to when certain implementations aren't available.
   */
  @VisibleForTesting
  static class GetCheckedTypeValidatorHolder {

    }

    override fun secureConnectEnd(
      call: Call,
      handshake: Handshake?,
    ) {
      logger.removeHandler(loggerHandler)
    }

    override fun callEnd(call: Call) {
      // Cleanup log handler if failed.
      logger.removeHandler(loggerHandler)
    }

    override fun connectionAcquired(
      call: Call,
      connection: Connection,
    ) {

        "ConnectionAcquired", "RequestHeadersStart", "RequestHeadersEnd", "ResponseHeadersStart",
        "ResponseHeadersEnd", "ResponseBodyStart", "ResponseBodyEnd", "ConnectionReleased",
        "CallEnd",
      ),
      eventListener.recordedEventTypes(),
    )

    eventListener.clearAllEvents()

    client.newCall(request).execute().use { response ->
      assertEquals(200, response.code)
    }

import static com.google.common.math.ReflectionFreeAssertThrows.assertThrows;
import static com.google.common.truth.Truth.assertThat;
import static java.math.RoundingMode.CEILING;
import static java.math.RoundingMode.DOWN;
import static java.math.RoundingMode.FLOOR;
import static java.math.RoundingMode.HALF_DOWN;
import static java.math.RoundingMode.HALF_EVEN;

                    if (logger.isInfoEnabled()) {
                        logger.info("Terminating indexUpdater. emptyListCount is over {}.", maxEmptyListCount);
                    }
                    // terminate crawling
                    finishCrawling = true;
                    forceStop();
                    if (fessConfig.getIndexerThreadDumpEnabledAsBoolean()) {
                        ThreadDumpUtil.printThreadDump();