if (set == null) {
        return ImmutableSet.of();
      }
      ImmutableSet<E> ret = ImmutableEnumSet.asImmutable(set);
      set = null; // subsequent manual manipulation of the accumulator mustn't affect ret
      return ret;
    }
  }

  @GwtIncompatible
  @SuppressWarnings({"rawtypes", "unchecked"})
  static <E extends Comparable<? super E>>

      if (set == null) {
        return ImmutableSet.of();
      }
      ImmutableSet<E> ret = ImmutableEnumSet.asImmutable(set);
      set = null; // subsequent manual manipulation of the accumulator mustn't affect ret
      return ret;
    }
  }

  @GwtIncompatible
  @SuppressWarnings({"rawtypes", "unchecked"})
  static <E extends Comparable<? super E>>

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

  /**
   * Returns a {@code Collector} that accumulates the input elements into a new {@code
   * ImmutableRangeMap}. As in {@link Builder}, overlapping ranges are not permitted.
   *
   * @since 33.2.0 (available since 23.1 in guava-jre)
   */

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

  /**
   * Returns a {@code Collector} that accumulates the input elements into a new {@code
   * ImmutableRangeMap}. As in {@link Builder}, overlapping ranges are not permitted.
   *
   * @since 23.1
   */

public abstract class ImmutableSortedMultiset<E> extends ImmutableMultiset<E>
    implements SortedMultiset<E> {
  // TODO(lowasser): GWT compatibility

  /**
   * Returns a {@code Collector} that accumulates the input elements into a new {@code
   * ImmutableMultiset}. Elements are sorted by the specified comparator.
   *
   * <p><b>Warning:</b> {@code comparator} should be <i>consistent with {@code equals}</i> as

 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public abstract class ImmutableBiMap<K, V> extends ImmutableMap<K, V> implements BiMap<K, V> {

  /**
   * Returns a {@link Collector} that accumulates elements into an {@code ImmutableBiMap} whose keys
   * and values are the result of applying the provided mapping functions to the input elements.
   * Entries appear in the result {@code ImmutableBiMap} in encounter order.
   *

import java.util.Arrays;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;

/**
 * An accumulator that selects the "top" {@code k} elements added to it, relative to a provided
 * comparator. "Top" can mean the greatest or the lowest elements, specified in the factory used to
 * create the {@code TopKSelector} instance.
 *

 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V>
    implements ListMultimap<K, V> {
  /**
   * Returns a {@link Collector} that accumulates elements into an {@code ImmutableListMultimap}
   * whose keys and values are the result of applying the provided mapping functions to the input
   * elements.
   *

@SuppressWarnings("serial") // we're overriding default serialization
public abstract class ImmutableList<E> extends ImmutableCollection<E>
    implements List<E>, RandomAccess {

  /**
   * Returns a {@code Collector} that accumulates the input elements into a new {@code
   * ImmutableList}, in encounter order.
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */

 *
 * @author Jared Levy
 * @since 2.0
 */
@GwtCompatible
public class ImmutableListMultimap<K, V> extends ImmutableMultimap<K, V>
    implements ListMultimap<K, V> {
  /**
   * Returns a {@link Collector} that accumulates elements into an {@code ImmutableListMultimap}
   * whose keys and values are the result of applying the provided mapping functions to the input
   * elements.
   *