/**
 * Unchecked variant of {@link java.util.concurrent.ExecutionException}. As with {@code
 * ExecutionException}, the exception's {@linkplain #getCause() cause} comes from a failed task,
 * possibly run in another thread.
 *
 * <p>{@code UncheckedExecutionException} is intended as an alternative to {@code
 * ExecutionException} when the exception thrown by a task is an unchecked exception. However, it

        assertEquals(1, response2.getNum());
        assertEquals(1, response2.getTotal());
    }

    @Test
    @SuppressWarnings("unchecked")
    public void test_indexFromDocument() throws Exception {
        SuggestSettings settings = suggester.settings();
        String field = settings.array().get(SuggestSettings.DefaultKeys.SUPPORTED_FIELDS)[0];

                    return singletonMap(entry.getKey(), entry.getValue());
                default:
                    return new MapN<>(map);
            }
        }
    }

    @SuppressWarnings("unchecked")
    static <K, V> Map<K, V> emptyMap() {
        return (Map<K, V>) EMPTY_MAP;
    }

    static <K, V> Map<K, V> singletonMap(K key, V value) {
        return new Map1<>(key, value);
    }

 *
 * @author Louis Wasserman
 */
@GwtIncompatible
public final class SafeTreeSet<E> implements Serializable, NavigableSet<E> {
  @SuppressWarnings("unchecked")
  private static final Comparator<Object> NATURAL_ORDER =
      (o1, o2) -> ((Comparable<Object>) o1).compareTo(o2);

  private final NavigableSet<E> delegate;

  public SafeTreeSet() {
    this(new TreeSet<E>());

    /** Gets the weak value reference held by entry. */
    WeakValueReference<K, V, E> getValueReference();
  }

  @SuppressWarnings("unchecked") // impl never uses a parameter or returns any non-null value
  static <K, V, E extends InternalEntry<K, V, E>>
      WeakValueReference<K, V, E> unsetWeakValueReference() {

    JAPAN,
    SWITZERLAND,
    UK
  }

  @AndroidIncompatible // test-suite builders
  public static final class EnumHashBiMapGenerator implements TestBiMapGenerator<Country, String> {
    @SuppressWarnings("unchecked")
    @Override
    public BiMap<Country, String> create(Object... entries) {
      BiMap<Country, String> result = EnumHashBiMap.create(Country.class);
      for (Object o : entries) {

    }
  }

  @SuppressWarnings("unchecked") // C can only be @Nullable Character or Character
  protected @NonNull C cellValue(Character character) {
    return (C) character;
  }

  // Only safe wrt. ClassCastException. Not null-safe (can be used to test expected Table NPEs)
  @SuppressWarnings("unchecked")
  protected C nullableCellValue(@Nullable Character character) {

   *
   * @since 7.0
   */
  @Override
  protected boolean standardContains(@Nullable Object object) {
    try {
      // any ClassCastExceptions and NullPointerExceptions are caught
      @SuppressWarnings({"unchecked", "nullness"})
      SortedSet<@Nullable Object> self = (SortedSet<@Nullable Object>) this;
      Object ceiling = self.tailSet(object).first();
      return unsafeCompare(comparator(), ceiling, object) == 0;

    public StandardKeySet() {
      super(ForwardingSortedMap.this);
    }
  }

  // unsafe, but worst case is a CCE or NPE is thrown, which callers will be expecting
  @SuppressWarnings({"unchecked", "nullness"})
  static int unsafeCompare(
      @Nullable Comparator<?> comparator, @Nullable Object o1, @Nullable Object o2) {
    if (comparator == null) {
      return ((Comparable<@Nullable Object>) o1).compareTo(o2);

   * @return {@code Optional.of(onlyElement)} if the stream has exactly one element (must not be
   *     {@code null}) and returns {@code Optional.empty()} if it has none.
   */
  @SuppressWarnings("unchecked")
  public static <T> Collector<T, ?, Optional<T>> toOptional() {
    return (Collector) TO_OPTIONAL;
  }

  private static final Object NULL_PLACEHOLDER = new Object();