public E last() {
    return delegate.last();
  }

  @Override
  public @Nullable E lower(E e) {
    return delegate.lower(checkValid(e));
  }

  @Override
  public @Nullable E pollFirst() {
    return delegate.pollFirst();
  }

  @Override
  public @Nullable E pollLast() {
    return delegate.pollLast();
  }

  @Override
  public boolean remove(Object object) {

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

/** A utility method to perform unchecked casts to suppress errors produced by nullness analyses. */
@GwtCompatible
@ElementTypesAreNonnullByDefault
final class NullnessCasts {
  /**
   * Accepts a {@code @Nullable T} and returns a plain {@code T}, without performing any check that
   * that conversion is safe.
   *

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

/** Implementation of {@link Futures#immediateFuture}. */
@GwtCompatible
@ElementTypesAreNonnullByDefault
// TODO(cpovirk): Make this final (but that may break Mockito spy calls).
class ImmediateFuture<V extends @Nullable Object> implements ListenableFuture<V> {
  static final ListenableFuture<?> NULL = new ImmediateFuture<@Nullable Object>(null);

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

/**
 * Derived suite generators for Guava collection interfaces, split out of the suite builders so that
 * they are available to GWT.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public final class DerivedGoogleCollectionGenerators {
  public static class MapGenerator<K extends @Nullable Object, V extends @Nullable Object>

 * <p>This testing utility is not thread-safe.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
public final class MinimalIterable<E extends @Nullable Object> implements Iterable<E> {
  /** Returns an iterable whose iterator returns the given elements in order. */
  public static <E extends @Nullable Object> MinimalIterable<E> of(E... elements) {
    // Make sure to get an unmodifiable iterator

        .addEqualityGroup(
            LENGTH_EQUIVALENCE.<@Nullable String>wrap(null),
            LENGTH_EQUIVALENCE.<@Nullable String>wrap(null))
        .addEqualityGroup(Equivalence.equals().wrap("hello"))
        .addEqualityGroup(Equivalence.equals().<@Nullable Object>wrap(null))
        .testEquals();
  }

  public void testWrap_get() {
    String test = "test";

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

/**
 * Skeletal implementation of {@link NavigableMap}.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
abstract class AbstractNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
    extends IteratorBasedAbstractMap<K, V> implements NavigableMap<K, V> {

  @Override

  ImmutableCollection() {}

  public abstract UnmodifiableIterator<E> iterator();

  public boolean contains(@Nullable Object object) {
    return object != null && super.contains(object);
  }

  public final boolean add(E e) {
    throw new UnsupportedOperationException();
  }

  public final boolean remove(@Nullable Object object) {
    throw new UnsupportedOperationException();
  }

import java.util.List;
import java.util.Map.Entry;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A container class for the five sample elements we need for testing.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class SampleElements<E extends @Nullable Object> implements Iterable<E> {
  // TODO: rename e3, e4 => missing1, missing2
  private final E e0;

import java.util.List;
import java.util.Map.Entry;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A container class for the five sample elements we need for testing.
 *
 * @author Kevin Bourrillion
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class SampleElements<E extends @Nullable Object> implements Iterable<E> {
  // TODO: rename e3, e4 => missing1, missing2
  private final E e0;