import java.util.NavigableSet;
import java.util.Optional;
import java.util.OptionalDouble;
import java.util.OptionalInt;
import java.util.OptionalLong;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.regex.Pattern;

   * <p>For all multimaps generated by the resulting builder, the {@link Multimap#keySet()} can be
   * safely cast to a {@link java.util.SortedSet}, and the {@link Multimap#asMap()} can safely be
   * cast to a {@link java.util.SortedMap}.
   */
  @SuppressWarnings("rawtypes")
  public static MultimapBuilderWithKeys<Comparable> treeKeys() {
    return treeKeys(Ordering.natural());
  }

  /**

import java.util.Optional;
import java.util.OptionalDouble;
import java.util.OptionalInt;
import java.util.OptionalLong;
import java.util.Queue;
import java.util.Random;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.UUID;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;

import java.util.Locale;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.Random;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.UUID;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;

import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.RandomAccess;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.function.BiPredicate;
import java.util.stream.Collector;
import java.util.stream.Stream;
import junit.framework.TestCase;

import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.RandomAccess;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeSet;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@code Multimaps}.
 *

     * @param m
     *            作成されるマップに配置されるマップ
     * @return {@link ConcurrentSkipListMap}の新しいインスタンス
     * @see ConcurrentSkipListMap#ConcurrentSkipListMap(SortedMap)
     */
    public static <K, V> ConcurrentSkipListMap<K, V> newConcurrentSkipListMap(final SortedMap<K, ? extends V> m) {
        return new ConcurrentSkipListMap<>(m);
    }

    /**
     * {@link ConcurrentSkipListSet}の新しいインスタンスを作成して返します。
     *

import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.regex.Pattern;

   * NavigableMap}, instead of the {@link java.util.Map} specified in the {@link Multimap}
   * interface.
   *
   * @since 14.0 (present with return type {@code SortedMap} since 2.0)
   */
  @Override
  public NavigableMap<K, Collection<V>> asMap() {
    return (NavigableMap<K, Collection<V>>) super.asMap();
  }

  /**

import java.util.Collections;
import java.util.Comparator;
import java.util.EnumMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.BiFunction;
import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;