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}.
 *

    }

    @Override
    public @Nullable Entry<K, V> firstEntry() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().firstEntry();
    }

    @Override
    public @Nullable Entry<K, V> floorEntry(K key) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().floorEntry(key);
    }

    @Override
    public @Nullable K floorKey(K key) {

    @Override
    public boolean equals(@Nullable Object other) {
      return (other instanceof ClassWhichIsAlwaysEqualButHasDifferentHashcodes);
    }
  }

  private static class ObjectWhichIsEqualButChangesClass implements Serializable {
    private static final long serialVersionUID = 1L;

    @Override
    public boolean equals(@Nullable Object other) {

  /** Prepares the multimap for unmodifiable tests, returning an unmodifiable view of the map. */
  private static Multimap<@Nullable String, @Nullable Integer> prepareUnmodifiableTests(
      Multimap<@Nullable String, @Nullable Integer> multimap,
      boolean permitsDuplicates,
      @Nullable String nullKey,
      @Nullable Integer nullValue) {
    multimap.clear();
    multimap.put("foo", 1);
    multimap.put("foo", 2);

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

/**
 * Creates maps, containing sample elements, to be tested.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface TestMapGenerator<K extends @Nullable Object, V extends @Nullable Object>
    extends TestContainerGenerator<Map<K, V>, Map.Entry<K, V>> {

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

/**
 * Creates maps, containing sample elements, to be tested.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public interface TestMapGenerator<K extends @Nullable Object, V extends @Nullable Object>
    extends TestContainerGenerator<Map<K, V>, Map.Entry<K, V>> {

  @VisibleForTesting final transient @Nullable Object[] elements;
  private final transient int hashCode;
  // 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;
  private final transient int size;

  RegularImmutableSet(

    return super.containsAll(collection);
  }

  @Override
  public Iterator<E> iterator() {
    return Arrays.asList(contents).iterator();
  }

  @Override
  public @Nullable Object[] toArray() {
    @Nullable Object[] result = new @Nullable Object[contents.length];
    System.arraycopy(contents, 0, result, 0, contents.length);
    return result;
  }

  /*

 *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
 *       to "undo" {@link ElementTypesAreNonnullByDefault}. It is the best we can do for Kotlin
 *       under our current constraints.
 *   <li>NullAway, which will <a
 *       href="https://github.com/google/guava/issues/6126#issuecomment-1204399671">treat it

 *       argument is non-nullable and (b) nullable when the type argument is nullable. We use this
 *       to "undo" {@link ElementTypesAreNonnullByDefault}. It is the best we can do for Kotlin
 *       under our current constraints.
 *   <li>NullAway, which will <a
 *       href="https://github.com/google/guava/issues/6126#issuecomment-1204399671">treat it