return (Optional<T>) INSTANCE;
  }

  private Absent() {}

  @Override
  public boolean isPresent() {
    return false;
  }

  @Override
  public T get() {
    throw new IllegalStateException("Optional.get() cannot be called on an absent value");
  }

  @Override
  public T or(T defaultValue) {
    return checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");

  public UnmodifiableIterator<E> descendingIterator() {
    return forward.iterator();
  }

  @Override
  @GwtIncompatible // NavigableSet
  ImmutableSortedSet<E> createDescendingSet() {
    throw new AssertionError("should never be called");
  }

  @Override
  public @Nullable E lower(E element) {
    return forward.higher(element);
  }

  @Override
  public @Nullable E floor(E element) {

    Thread interruptee = Thread.currentThread();
    new Thread(
            () -> {
              try {
                unit.sleep(time);
              } catch (InterruptedException wontHappen) {
                throw new AssertionError(wontHappen);
              }
              interruptee.interrupt();
            })
        .start();
  }

  static void repeatedlyInterruptTestThread(TearDownAccepter tearDownAccepter) {

 */
public class StandaloneRestTestPlugin implements Plugin<Project> {
    @Override
    public void apply(final Project project) {
        if (project.getPluginManager().hasPlugin("elasticsearch.build")) {
            throw new InvalidUserDataException(
                "elasticsearch.standalone-test, elasticsearch.standalone-rest-test, " + "and elasticsearch.build are mutually exclusive"
            );
        }

   *       href="https://github.com/google/guava/wiki/GraphsExplained#graph-elements-nodes-and-edges">
   *       graph elements</a> for details)
   * </ul>
   *
   * @throws IllegalArgumentException if {@code node} is not an element of this graph
   */
  Iterable<? extends N> predecessors(N node);

   *       href="https://github.com/google/guava/wiki/GraphsExplained#graph-elements-nodes-and-edges">
   *       graph elements</a> for details)
   * </ul>
   *
   * @throws IllegalArgumentException if {@code node} is not an element of this graph
   */
  Iterable<? extends N> successors(N node);

    }
    constructor.setAccessible(true); // accessibility check is too slow
    try {
      return constructor.newInstance();
    } catch (InstantiationException | IllegalAccessException impossible) {
      throw new AssertionError(impossible);
    } catch (InvocationTargetException e) {
      logger.log(Level.WARNING, "Exception while invoking default constructor.", e.getCause());
      return arbitraryConstantInstanceOrNull(type);

      return false;
    }

    addNodeInternal(node);
    return true;
  }

  /**
   * Adds {@code node} to the graph and returns the associated {@link GraphConnections}.
   *
   * @throws IllegalStateException if {@code node} is already present
   */
  @CanIgnoreReturnValue
  private GraphConnections<N, V> addNodeInternal(N node) {
    GraphConnections<N, V> connections = newConnections();

public class FessJsonResourceProviderTest extends UnitFessTestCase {

    private FessJsonResourceProvider provider;

    @Override
    protected void setUp(TestInfo testInfo) throws Exception {
        super.setUp(testInfo);
        provider = new FessJsonResourceProvider();
    }

    @Test
    public void test_isNullsSuppressed() {
        // Test that nulls are suppressed

    }

    @Test
    void testDelete_ng() {
        checkDeleteMethod(Collections.emptyMap()).then().body("response.status", equalTo(1));
    }

    @Test
    void testCRUD() throws Exception {
        List<Map<String, Object>> available =
                checkGetMethod(Collections.emptyMap(), getAvailableEndpointSuffix() + "/").body().jsonPath().get("response.plugins");