ImmutableSortedMap::copyOfSorted);
  }

  // unsafe, comparator() returns a comparator on the specified type
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableSortedMap<K, V> of() {
    return new Builder<K, V>((Comparator<K>) NATURAL_ORDER).build();
  }

  public static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> of(K k1, V v1) {

          .put(Map.class, ImmutableMap.of())
          .put(ImmutableMap.class, ImmutableMap.of())
          .put(SortedMap.class, ImmutableSortedMap.of())
          .put(ImmutableSortedMap.class, ImmutableSortedMap.of())
          .put(NavigableMap.class, Maps.unmodifiableNavigableMap(Maps.newTreeMap()))
          .put(Multimap.class, ImmutableMultimap.of())

     */
    return Collector.of(
        () -> new ImmutableSortedMap.Builder<K, V>(comparator),
        (builder, input) -> builder.put(keyFunction.apply(input), valueFunction.apply(input)),
        ImmutableSortedMap.Builder::combine,
        ImmutableSortedMap.Builder::buildOrThrow,
        Collector.Characteristics.UNORDERED);
  }

          .put(Map.class, ImmutableMap.of())
          .put(ImmutableMap.class, ImmutableMap.of())
          .put(SortedMap.class, ImmutableSortedMap.of())
          .put(ImmutableSortedMap.class, ImmutableSortedMap.of())
          .put(NavigableMap.class, Maps.unmodifiableNavigableMap(Maps.newTreeMap()))
          .put(Multimap.class, ImmutableMultimap.of())

import com.google.common.collect.ImmutableMultiset;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.ImmutableSortedMap;
import com.google.common.collect.ImmutableSortedMultiset;
import com.google.common.collect.ImmutableSortedSet;
import com.google.common.collect.ImmutableTable;
import com.google.common.collect.LinkedHashMultimap;

    assertEquals(ImmutableMap.of(), ArbitraryInstances.get(ImmutableMap.class));
    assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(SortedMap.class));
    assertEquals(ImmutableSortedMap.of(), ArbitraryInstances.get(ImmutableSortedMap.class));
    assertEquals(ImmutableMultiset.of(), ArbitraryInstances.get(Multiset.class));

        return new ConcurrentSkipListMap<>(map);
      }
    },
    ImmutableSortedMapImpl {
      @Override
      public <K extends Comparable<K>, V> SortedMap<K, V> create(Map<K, V> map) {
        return ImmutableSortedMap.copyOf(map);
      }
    };
  }

  enum BiMapImpl implements MapsImplEnum {
    HashBiMapImpl {
      @Override
      public <K extends Comparable<K>, V> BiMap<K, V> create(Map<K, V> map) {

    if (ranges.isEmpty()) {
      return ImmutableMap.of();
    }
    RegularImmutableSortedSet<Range<K>> rangeSet =
        new RegularImmutableSortedSet<>(ranges, Range.<K>rangeLexOrdering());
    return new ImmutableSortedMap<>(rangeSet, values);
  }

  @Override
  public ImmutableMap<Range<K>, V> asDescendingMapOfRanges() {
    if (ranges.isEmpty()) {
      return ImmutableMap.of();
    }

import com.google.common.collect.ImmutableMultiset;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.ImmutableSortedMap;
import com.google.common.collect.ImmutableSortedMultiset;
import com.google.common.collect.ImmutableSortedSet;
import com.google.common.collect.ImmutableTable;
import com.google.common.collect.LinkedHashMultimap;

    TreeMap<K, V> map = Maps.newTreeMap();
    map.put(key, value);
    return map;
  }

  @Generates
  static <K extends Comparable<? super K>, V> ImmutableSortedMap<K, V> generateImmutableSortedMap(
      K key, V value) {
    return ImmutableSortedMap.of(key, value);
  }

  @Generates
  static <K, V> Multimap<K, V> generateMultimap(@Nullable K key, @Nullable V value) {
    return generateListMultimap(key, value);