*
   * @since 10.0
   */
  public static final class Wrapper<T extends @Nullable Object> implements Serializable {
    /*
     * Equivalence's type argument is always non-nullable: Equivalence<Number>, never
     * Equivalence<@Nullable Number>. That can still produce wrappers of various types --
     * Wrapper<Number>, Wrapper<Integer>, Wrapper<@Nullable Integer>, etc. If we used just

import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A mutable type-to-instance map. See also {@link ImmutableTypeToInstanceMap}.
 *
 * @author Ben Yu
 * @since 13.0
 */
@ElementTypesAreNonnullByDefault
public final class MutableTypeToInstanceMap<B extends @Nullable Object>
    extends ForwardingMap<TypeToken<? extends @NonNull B>, B> implements TypeToInstanceMap<B> {

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Multimaps#filterKeys(ListMultimap, Predicate)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
final class FilteredKeyListMultimap<K extends @Nullable Object, V extends @Nullable Object>
    extends FilteredKeyMultimap<K, V> implements ListMultimap<K, V> {

 * limitations under the License.
 */

package com.google.common.collect;

import java.util.Collection;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A GWT-only class only used by GWT emulations. It is used to consolidate the definitions of method
 * delegation to save code size.
 *
 * @author Hayward Chan
 */

   * 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);

@ElementTypesAreNonnullByDefault
class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {
  // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement

  /** Creates an empty {@code CompactLinkedHashMap} instance. */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      CompactLinkedHashMap<K, V> create() {

import junit.framework.Assert;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A test utility that verifies that your methods and constructors throw {@link
 * NullPointerException} or {@link UnsupportedOperationException} whenever null is passed to a
 * parameter whose declaration or type isn't annotated with an annotation with the simple name
 * {@code Nullable}, {@code CheckForNull}, {@code NullableType}, or {@code NullableDecl}.
 *

  private static final Iterable<@Nullable Integer> ITERABLE_NULL = Arrays.asList((Integer) null);
  private static final Iterable<@Nullable Integer> ITERABLE_NULL_NULL =
      Arrays.asList((Integer) null, null);
  private static final Iterable<@Nullable Integer> ITERABLE_NULL_1 = Arrays.asList(null, 1);
  private static final Iterable<@Nullable Integer> ITERABLE_1_NULL = Arrays.asList(1, null);

  @Override
  @ParametricNullness
  public <T extends @Nullable Object> T callWithTimeout(
      Callable<T> callable, long timeoutDuration, TimeUnit timeoutUnit) throws ExecutionException {
    checkNotNull(callable);
    checkNotNull(timeoutUnit);
    try {
      return callable.call();
    } catch (RuntimeException e) {
      throw new UncheckedExecutionException(e);

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * An iterator that transforms a backing list iterator; for internal use. This avoids the object
 * overhead of constructing a {@link Function} for internal methods.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
abstract class TransformedListIterator<F extends @Nullable Object, T extends @Nullable Object>