*       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code

 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code

  // See the note about volatile in the superclass.
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry1;
  private transient volatile @Nullable CacheEntry<K, V> cacheEntry2;

  MapRetrievalCache(Map<K, V> backingMap) {
    super(backingMap);
  }

  @SuppressWarnings("unchecked") // Safe because we only cast if key is found in map.
  @Override
  @Nullable V get(Object key) {
    checkNotNull(key);
    V value = getIfCached(key);

  // the same values as `elements` in hashed positions (plus nulls)
  @VisibleForTesting final transient @Nullable Object[] table;
  // 'and' with an int to get a valid table index.
  private final transient int mask;

  RegularImmutableSet(Object[] elements, int hashCode, @Nullable Object[] table, int mask) {
    this.elements = elements;
    this.hashCode = hashCode;
    this.table = table;
    this.mask = mask;

    READY,
    NOT_READY,
    DONE,
    FAILED,
  }

  private @Nullable T next;

  protected abstract @Nullable T computeNext();

  @CanIgnoreReturnValue
  protected final @Nullable T endOfData() {
    state = State.DONE;
    return null;
  }

  @Override
  public final boolean hasNext() {
    checkState(state != State.FAILED);
    switch (state) {
      case DONE:
        return false;

     * Check if the personality is "maven3".
     */
    public static boolean mavenMaven3Personality(@Nullable Map<String, ?> userProperties) {
        return doGet(userProperties, Constants.MAVEN_MAVEN3_PERSONALITY, false);
    }

    /**
     * Check if the consumer POM feature is active.
     */
    public static boolean consumerPom(@Nullable Map<String, ?> userProperties) {

     */
    public static int main(
            String[] args,
            ClassWorld world,
            @Nullable InputStream stdIn,
            @Nullable OutputStream stdOut,
            @Nullable OutputStream stdErr)
            throws IOException {
        return new MavenEncCling(world).run(args, stdIn, stdOut, stdErr, true);
    }

    public MavenEncCling() {

     */
    public static int main(
            String[] args,
            ClassWorld world,
            @Nullable InputStream stdIn,
            @Nullable OutputStream stdOut,
            @Nullable OutputStream stdErr)
            throws IOException {
        return new MavenShellCling(world).run(args, stdIn, stdOut, stdErr, true);
    }

    public MavenShellCling() {

  }

  @Override
  public @Nullable V value(N node) {
    return adjacentNodeValues.get(node);
  }

  @Override
  public void removePredecessor(N node) {
    @SuppressWarnings("unused")
    V unused = removeSuccessor(node);
  }

  @Override
  public @Nullable V removeSuccessor(N node) {
    return adjacentNodeValues.remove(node);
  }

  @Override

   * href="http://gee.cs.oswego.edu/dl/html/StreamParallelGuidance.html">efficiently splittable</a>.
   * This may harm parallel performance.
   */
  @Beta
  public static <A extends @Nullable Object, B extends @Nullable Object, R extends @Nullable Object>
      Stream<R> zip(
          Stream<A> streamA, Stream<B> streamB, BiFunction<? super A, ? super B, R> function) {
    checkNotNull(streamA);
    checkNotNull(streamB);