} else {
                    logger.warn("Unexpected response processor: expected=DefaultResponseProcessor, actual={}, url={}",
                            responseProcessor.getClass().getSimpleName(), url);
                }
            }
            return null;
        } catch (final ChildUrlsException | DataStoreCrawlingException e) {
            throw e;
        } catch (final Exception e) {

     */
    public void register(final RankFusionSearcher searcher) {
        if (logger.isDebugEnabled()) {
            logger.debug("Registering searcher: {}", searcher.getClass().getSimpleName());
        }
        searchers.add(searcher);
        synchronized (this) {
            if (executorService == null) {
                int numThreads = ComponentUtil.getFessConfig().getRankFusionThreadsAsInteger();

  }

  private static boolean containsNullable(Annotation[] annotations) {
    for (Annotation annotation : annotations) {
      if (NULLABLE_ANNOTATION_SIMPLE_NAMES.contains(annotation.annotationType().getSimpleName())) {
        return true;
      }
    }
    return false;
  }

  private boolean isIgnored(Member member) {
    return member.isSynthetic()
        || ignoredMembers.contains(member)

  private static <T> T expectArgument(Class<T> type, Object arg) {
    try {
      return type.cast(arg);
    } catch (ClassCastException e) {
      throw new IllegalArgumentException(arg + " is not a " + type.getSimpleName());
    }
  }

  /** A TypeTable maintains mapping from {@link TypeVariable} to types. */
  private static class TypeTable {
    private final ImmutableMap<TypeVariableKey, Type> map;

    TypeTable() {

   * used in exception and warning output.
   */
  private static String getLockName(Enum<?> rank) {
    return rank.getDeclaringClass().getSimpleName() + "." + rank.name();
  }

  /**
   * A {@code CycleDetectingLockFactory.WithExplicitOrdering} provides the additional enforcement of

  }

  private static boolean containsNullable(Annotation[] annotations) {
    for (Annotation annotation : annotations) {
      if (NULLABLE_ANNOTATION_SIMPLE_NAMES.contains(annotation.annotationType().getSimpleName())) {
        return true;
      }
    }
    return false;
  }

  private boolean isIgnored(Member member) {
    return member.isSynthetic()
        || ignoredMembers.contains(member)

    }
    // generateInt() is 1-based.
    return Iterables.get(instances, (generateInt() - 1) % instances.size());
  }

  private static String paramString(Class<?> type, int i) {
    return type.getSimpleName() + '@' + i;
  }

  /**
   * Annotates a method to be the instance generator of a certain type. The return type is the
   * generated type. The method parameters correspond to the generated type's type parameters. For

   * Returns the name of this service. {@link AbstractScheduledService} may include the name in
   * debugging output.
   *
   * @since 14.0
   */
  protected String serviceName() {
    return getClass().getSimpleName();
  }

  @Override
  public String toString() {
    return serviceName() + " [" + state() + "]";
  }

  @Override
  public final boolean isRunning() {
    return delegate.isRunning();

    }
    // generateInt() is 1-based.
    return Iterables.get(instances, (generateInt() - 1) % instances.size());
  }

  private static String paramString(Class<?> type, int i) {
    return type.getSimpleName() + '@' + i;
  }

  /**
   * Annotates a method to be the instance generator of a certain type. The return type is the
   * generated type. The method parameters correspond to the generated type's type parameters. For

   * Returns the name of this service. {@link AbstractScheduledService} may include the name in
   * debugging output.
   *
   * @since 14.0
   */
  protected String serviceName() {
    return getClass().getSimpleName();
  }

  @Override
  public String toString() {
    return serviceName() + " [" + state() + "]";
  }

  @Override
  public final boolean isRunning() {
    return delegate.isRunning();