/**
   * Returns a builder that creates immutable sorted maps whose keys are ordered by their natural
   * ordering. The sorted maps use {@link Ordering#natural()} as the comparator.
   */
  public static <K extends Comparable<?>, V> Builder<K, V> naturalOrder() {
    return new Builder<>(Ordering.natural());
  }

  /**
   * Returns a builder that creates immutable sorted maps with an explicit comparator. If the

    if (uniques < contents.length / 2) {
      // Deduplication eliminated many of the elements.  We don't want to retain an arbitrarily
      // large array relative to the number of elements, so we cap the ratio.
      contents = Arrays.copyOf(contents, uniques);
    }
    return new RegularImmutableSortedSet<E>(
        ImmutableList.<E>asImmutableList(contents, uniques), comparator);
  }

  /**

        "Multiple entries with same " + conflictDescription + ": " + entry1 + " and " + entry2);
  }

  /**
   * A builder for creating immutable map instances, especially {@code public static final} maps
   * ("constant maps"). Example:
   *
   * <pre>{@code
   * static final ImmutableMap<String, Integer> WORD_TO_INT =
   *     new ImmutableMap.Builder<String, Integer>()
   *         .put("one", 1)

  /** Returns a new builder for an immutable range map. */
  public static <K extends Comparable<?>, V> Builder<K, V> builder() {
    return new Builder<>();
  }

  /**
   * A builder for immutable range maps. Overlapping ranges are prohibited.
   *
   * @since 14.0
   */
  @DoNotMock
  public static final class Builder<K extends Comparable<?>, V> {
    private final List<Entry<Range<K>, V>> entries;

     */
    Waiter(boolean unused) {}

    Waiter() {
      // avoid volatile write, write is made visible by subsequent CAS on waiters field
      ATOMIC_HELPER.putThread(this, Thread.currentThread());
    }

    // non-volatile write to the next field. Should be made visible by subsequent CAS on waiters
    // field.
    void setNext(@CheckForNull Waiter next) {
      ATOMIC_HELPER.putNext(this, next);
    }

 * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#maps">{@code Maps}</a>.
 *
 * @author Kevin Bourrillion
 * @author Mike Bostock
 * @author Isaac Shum
 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public final class Maps {
  private Maps() {}

  private enum EntryFunction implements Function<Entry<?, ?>, @Nullable Object> {

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

/**
 * Static utility methods pertaining to {@link Set} instances. Also see this class's counterparts
 * {@link Lists}, {@link Maps} and {@link Queues}.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/CollectionUtilitiesExplained#sets">{@code Sets}</a>.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy

      Collection<Entry<K, V>> unmodifiableEntries(Collection<Entry<K, V>> entries) {
    if (entries instanceof Set) {
      return Maps.unmodifiableEntrySet((Set<Entry<K, V>>) entries);
    }
    return new Maps.UnmodifiableEntries<>(Collections.unmodifiableCollection(entries));
  }

  /**

    return new ByFunctionOrdering<>(function, this);
  }

  <T2 extends T> Ordering<Entry<T2, ?>> onKeys() {
    return onResultOf(Maps.<T2>keyFunction());
  }

  /**
   * Returns an ordering which first uses the ordering {@code this}, but which in the event of a

    }

    @Override
    Set<K> createKeySet() {
      @WeakOuter
      class KeySetImpl extends Maps.KeySet<K, Collection<V>> {
        KeySetImpl() {
          super(AsMap.this);
        }

        @Override
        public boolean removeAll(Collection<?> c) {
          return removeEntriesIf(Maps.<K>keyPredicateOnEntries(in(c)));
        }

        @Override