.build();

  /**
   * type → implementation. Inherently mutable interfaces and abstract classes are mapped to their
   * default implementations and are "new"d upon get().
   */
  private static final ConcurrentMap<Class<?>, Class<?>> implementations = Maps.newConcurrentMap();

  private static <T> void setImplementation(Class<T> type, Class<? extends T> implementation) {

/**
 * The concurrent hash map implementation built by {@link MapMaker}.
 *
 * <p>This implementation is heavily derived from revision 1.96 of <a
 * href="http://tinyurl.com/ConcurrentHashMap">ConcurrentHashMap.java</a>.
 *
 * @param <K> the type of the keys in the map
 * @param <V> the type of the values in the map
 * @param <E> the type of the {@link InternalEntry} entry implementation used internally

          .build();

  /**
   * type → implementation. Inherently mutable interfaces and abstract classes are mapped to their
   * default implementations and are "new"d upon get().
   */
  private static final ConcurrentMap<Class<?>, Class<?>> implementations = Maps.newConcurrentMap();

  private static <T> void setImplementation(Class<T> type, Class<? extends T> implementation) {

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Multiset implementation that uses hashing for key and entry access.
 *
 * @author Kevin Bourrillion
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible(serializable = true, emulated = true)
@ElementTypesAreNonnullByDefault

    return LexicographicalComparatorHolder.PureJavaComparator.INSTANCE;
  }

  /**
   * Provides a lexicographical comparator implementation; either a Java implementation or a faster
   * implementation based on {@link Unsafe}.
   *
   * <p>Uses reflection to gracefully fall back to the Java implementation if {@code Unsafe} isn't
   * available.
   */
  @VisibleForTesting
  static class LexicographicalComparatorHolder {

 *
 * <p>This uses the same efficient implementation as {@link Ordering#leastOf(Iterable, int)},
 * offering expected O(n + k log k) performance (worst case O(n log k)) for n calls to {@link
 * #offer} and a call to {@link #topK}, with O(k) memory. In comparison, quickselect has the same
 * asymptotics but requires O(n) memory, and a {@code PriorityQueue} implementation takes O(n log

   * to custom TypeVariable implementations. As a result, we need to make sure our TypeVariable
   * implementation respects symmetry. Moreover, we don't want to reconstruct a native type variable
   * {@code <A>} using our implementation unless some of its bounds have changed in resolution. This
   * avoids creating unequal TypeVariable implementation unnecessarily. When the bounds do change,

    return LexicographicalComparatorHolder.PureJavaComparator.INSTANCE;
  }

  /**
   * Provides a lexicographical comparator implementation; either a Java implementation or a faster
   * implementation based on {@link Unsafe}.
   *
   * <p>Uses reflection to gracefully fall back to the Java implementation if {@code Unsafe} isn't
   * available.
   */
  @VisibleForTesting
  static class LexicographicalComparatorHolder {

 *       worse, and possibly better, than creating a mutable collection and copying it.
 *   <li>Implementations generally do not cache hash codes. If your element or key type has a slow
 *       {@code hashCode} implementation, it should cache it itself.
 * </ul>
 *
 * <h4>Example usage</h4>
 *
 * <pre>{@code
 * class Foo {

      }
      return max(estimatedSize, 0);
    }

    @Override
    public final int characteristics() {
      return characteristics;
    }
  }

  /**
   * Implementation of {@link Stream#flatMap} with an object spliterator output type.
   *
   * <p>To avoid having this type, we could use {@code FlatMapSpliterator} directly. The main