*/
  private static final SuccessorsFunction<Character> TWO_CYCLES_GRAPH =
      createDirectedGraph("ab", "ac", "bc", "cd", "da");

  /**
   * A tree-shaped graph that looks as follows (all edges are directed facing downwards):
   *
   * {@snippet :
   *        h
   *       /|\
   *      / | \
   *     /  |  \
   *    d   e   g
   *   /|\      |
   *  / | \     |
   * a  b  c    f
   * }
   */

import java.lang.reflect.Method;
import java.util.Locale;
import junit.framework.TestCase;

/**
 * Since annotations have some reusability issues that force copy and paste all over the place, it's
 * worth having a test to ensure that all our Feature enums have their annotations correctly set up.
 *
 * @author George van den Driessche
 */
public class FeatureEnumTest extends TestCase {

  /**
   * Returns an output {@code Future} to use in place of the given {@code input}. The output {@code
   * Future} need not be {@linkplain Future#isDone done}, making {@code AsyncFunction} suitable for
   * asynchronous derivations.
   *
   * <p>Throwing an exception from this method is equivalent to returning a failing {@code Future}.
   */

 */
@FunctionalInterface
@GwtCompatible
public interface AsyncCallable<V extends @Nullable Object> {
  /**
   * Computes a result {@code Future}. The output {@code Future} need not be {@linkplain
   * Future#isDone done}, making {@code AsyncCallable} suitable for asynchronous derivations.
   *
   * <p>Throwing an exception from this method is equivalent to returning a failing {@link
   * ListenableFuture}.
   */

  fun newBuilder(): Builder = commonNewBuilder()

  /**
   * Returns true if `other` is a `Headers` object with the same headers, with the same casing, in
   * the same order. Note that two headers instances may be *semantically* equal but not equal
   * according to this method. In particular, none of the following sets of headers are equal
   * according to this method:

KEP: https://github.com/kubernetes/enhancements/issues/<kep-issue-number>

If there is no associated issue, then write "N/A".
-->

#### Special notes for your reviewer:

#### Does this PR introduce a user-facing change?
<!--
If no, just write "NONE" in the release-note block below.
If yes, a release note is required:

totype={constructor:at,init:function(e,t,n,r,i,o){this.elem=e,this.prop=n,this.easing=i||ce.easing._default,this.options=t,this.start=this.now=this.cur(),this.end=r,this.unit=o||(ce.cssNumber[n]?"":"px")},cur:function(){var e=at.propHooks[this.prop];return e&&e.get?e.get(this):at.propHooks._default.get(this)},run:function(e){var t,n=at.propHooks[this.prop];return this.options.duration?this.pos=t=ce.easing[this.easing](e,this.options.duration*e,0,1,this.options.duration):this.pos=t=e,this.now=(th...

    elements.add(null);
    collection = getSubjectGenerator().create(elements.toArray());
    assertEquals(
        "A Set's hashCode() should be the sum of those of its elements (with "
            + "a null element counting as having a hash of zero).",
        expectedHashCode,
        getSet().hashCode());
  }

  /**
   * Returns the {@link Method} instances for the test methods in this class which call {@code

  private final Set<Type> visited = new HashSet<>();

  /**
   * Visits the given types. Null types are ignored. This allows subclasses to call {@code
   * visit(parameterizedType.getOwnerType())} safely without having to check nulls.
   */
  public final void visit(@Nullable Type... types) {
    for (Type type : types) {
      if (type == null || !visited.add(type)) {
        // null owner type, or already visited;
        continue;

  private final boolean allowNulls;

  // Package-private so that it can be extended.
  MinimalCollection(Class<? super @NonNull E> type, boolean allowNulls, E... contents) {
    // TODO: consider making it shuffle the contents to test iteration order.
    this.contents = Platform.clone(contents);
    this.type = type;
    this.allowNulls = allowNulls;

    if (!allowNulls) {
      for (Object element : contents) {