return new SupplierComposition<>(function, supplier);
  }

  private static class SupplierComposition<F extends @Nullable Object, T extends @Nullable Object>
      implements Supplier<T>, Serializable {
    final Function<? super F, T> function;
    final Supplier<F> supplier;

    SupplierComposition(Function<? super F, T> function, Supplier<F> supplier) {

   * AnnotatedElement}, which {@code TypeVariable} began to extend only in Java 8. Those methods
   * refer only to types present in Java 7, so we could implement them in {@code TypeVariableImpl}
   * today. (We could probably then make {@code TypeVariableImpl} implement {@code AnnotatedElement}
   * so that we get partial compile-time checking.)
   *

 * our other nullness annotations.
 */
final class Synchronized {
  private Synchronized() {}

  static class SynchronizedObject implements Serializable {
    final Object delegate;
    final Object mutex;

    SynchronizedObject(Object delegate, @CheckForNull Object mutex) {
      this.delegate = checkNotNull(delegate);

@SuppressWarnings("serial") // we're overriding default serialization
@ElementTypesAreNonnullByDefault
public abstract class ImmutableMultiset<E> extends ImmutableMultisetGwtSerializationDependencies<E>
    implements Multiset<E> {

  /**
   * Returns a {@code Collector} that accumulates the input elements into a new {@code
   * ImmutableMultiset}. Elements iterate in order by the <i>first</i> appearance of that element in

    return checkNotNull(multiset);
  }

  static class UnmodifiableMultiset<E extends @Nullable Object> extends ForwardingMultiset<E>
      implements Serializable {
    final Multiset<? extends E> delegate;

    UnmodifiableMultiset(Multiset<? extends E> delegate) {
      this.delegate = delegate;
    }

    @SuppressWarnings("unchecked")

 *
 * @author Louis Wasserman
 * @since 14.0
 */
@GwtIncompatible // NavigableMap
@ElementTypesAreNonnullByDefault
public class ImmutableRangeMap<K extends Comparable<?>, V> implements RangeMap<K, V>, Serializable {

  private static final ImmutableRangeMap<Comparable<?>, Object> EMPTY =
      new ImmutableRangeMap<>(ImmutableList.<Range<Comparable<?>>>of(), ImmutableList.of());

  /**

 * @author Louis Wasserman
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class ForwardingMapEntry<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingObject implements Map.Entry<K, V> {
  // TODO(lowasser): identify places where thread safety is actually lost

  /** Constructor for use by subclasses. */
  protected ForwardingMapEntry() {}

  @Override

    assertMapEquals(copy, "two", 2, "three", 3, "one", 1);
    assertSame(copy, ImmutableSortedMap.copyOfSorted(copy));
    assertSame(comparator, copy.comparator());
  }

  private static class IntegerDiv10 implements Comparable<IntegerDiv10> {
    final int value;

    IntegerDiv10(int value) {
      this.value = value;
    }

    @Override
    public int compareTo(IntegerDiv10 o) {

  /**
   * Compare strings lengths, and if the lengths are equal compare the strings. A {@code null} is
   * less than any non-null value.
   */
  private enum StringLength implements Comparator<@Nullable String> {
    COMPARATOR;

    @Override
    public int compare(@Nullable String first, @Nullable String second) {
      if (first == second) {
        return 0;

 * @author Louis Wasserman
 * @since 2.0 (implements {@code NavigableSet} since 12.0)
 */
// TODO(benyu): benchmark and optimize all creation paths, which are a mess now
@GwtCompatible(serializable = true, emulated = true)
@SuppressWarnings("serial") // we're overriding default serialization
@ElementTypesAreNonnullByDefault
public abstract class ImmutableSortedSet<E> extends ImmutableSet<E>
    implements NavigableSet<E>, SortedIterable<E> {
  /**