- **ResponseProcessor**: `DefaultResponseProcessor`, `SitemapsResponseProcessor`, `NullResponseProcessor`
- **Transformer**: `HtmlTransformer`, `XmlTransformer`, `FileTransformer`, etc.
- **Extractor**: Weight-based selection (tries in descending weight order)

### Key Extractors

`TikaExtractor`, `PdfExtractor`, `MsWordExtractor`, `MsExcelExtractor`, `MsPowerPointExtractor`, `ZipExtractor`, `HtmlExtractor`, `MarkdownExtractor`, `EmlExtractor`

      Assert.assertTrue(
          factory + " returns null but it's not annotated with @Nullable", isNullable(factory));
    }
    return returnValue;
  }

  /**
   * Thrown if the test tries to invoke a constructor or static factory method but failed because
   * the dummy value of a constructor or method parameter is unknown.
   */
  @VisibleForTesting

   * }
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  public static void awaitClear(WeakReference<?> ref) {
    awaitDone(() -> ref.get() == null);
  }

  /**
   * Tries to perform a "full" garbage collection cycle (including processing of weak references and
   * invocation of finalize methods) and waits for it to complete. Ensures that at least one weak

   * }
   *
   * @throws RuntimeException if timed out or interrupted while waiting
   */
  public static void awaitClear(WeakReference<?> ref) {
    awaitDone(() -> ref.get() == null);
  }

  /**
   * Tries to perform a "full" garbage collection cycle (including processing of weak references and
   * invocation of finalize methods) and waits for it to complete. Ensures that at least one weak

     * can't load it.
     *
     * @throws SecurityException if we don't have the appropriate privileges
     */
    @Nullable Class<?> loadFinalizer();
  }

  /**
   * Tries to load Finalizer from the system class loader. If Finalizer is in the system class path,
   * we needn't create a separate loader.
   */
  static final class SystemLoader implements FinalizerLoader {

     * can't load it.
     *
     * @throws SecurityException if we don't have the appropriate privileges
     */
    @Nullable Class<?> loadFinalizer();
  }

  /**
   * Tries to load Finalizer from the system class loader. If Finalizer is in the system class path,
   * we needn't create a separate loader.
   */
  static final class SystemLoader implements FinalizerLoader {

  }

  private class ThreadedService extends AbstractService {
    final CountDownLatch hasConfirmedIsRunning = new CountDownLatch(1);

    /*
     * The main test thread tries to stop() the service shortly after
     * confirming that it is running. Meanwhile, the service itself is trying
     * to confirm that it is running. If the main thread's stop() call happens

  }

  private class ThreadedService extends AbstractService {
    final CountDownLatch hasConfirmedIsRunning = new CountDownLatch(1);

    /*
     * The main test thread tries to stop() the service shortly after
     * confirming that it is running. Meanwhile, the service itself is trying
     * to confirm that it is running. If the main thread's stop() call happens

  /**
   * This is a less carefully-controlled version of {@link #testRemovalNotification_clear} - this is
   * a black-box test that tries to create lots of different thread-interleavings, and asserts that
   * each computation is affected by a call to {@code clear()} (and therefore gets passed to the

  /**
   * This is a less carefully-controlled version of {@link #testRemovalNotification_clear} - this is
   * a black-box test that tries to create lots of different thread-interleavings, and asserts that
   * each computation is affected by a call to {@code clear()} (and therefore gets passed to the