FIELD com.google.common.collect.AbstractMultiset.entrySet com.google.common.collect.FilteredEntryMultimap.Keys.entrySet.$
FIELD com.google.common.collect.ConcurrentHashMultiset.countMap
FIELD com.google.common.collect.ImmutableMultiset.asList
FIELD com.google.common.collect.ImmutableRangeMap.ranges
FIELD com.google.common.collect.ImmutableRangeSet.ranges
FIELD com.google.common.collect.ImmutableSet.asList

  }

  static <E extends @Nullable Object> Multiset<E> multiset(
      Multiset<E> multiset, @Nullable Object mutex) {
    if (multiset instanceof SynchronizedMultiset || multiset instanceof ImmutableMultiset) {
      return multiset;
    }
    return new SynchronizedMultiset<>(multiset, mutex);
  }

  static final class SynchronizedMultiset<E extends @Nullable Object>

  }

  static <E extends @Nullable Object> Multiset<E> multiset(
      Multiset<E> multiset, @Nullable Object mutex) {
    if (multiset instanceof SynchronizedMultiset || multiset instanceof ImmutableMultiset) {
      return multiset;
    }
    return new SynchronizedMultiset<>(multiset, mutex);
  }

  static final class SynchronizedMultiset<E extends @Nullable Object>

      }
    },
    ImmutableMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {
        return ImmutableMultiset.copyOf(contents);
      }
    };
  }

  enum SortedMultisetImpl implements CollectionsImplEnum {
    TreeMultisetImpl {
      @Override

      }
    },
    ImmutableMultisetImpl {
      @Override
      public <E extends Comparable<E>> Multiset<E> create(Collection<E> contents) {
        return ImmutableMultiset.copyOf(contents);
      }
    };
  }

  enum SortedMultisetImpl implements CollectionsImplEnum {
    TreeMultisetImpl {
      @Override

    assertThat(Iterables.unmodifiableIterable((List<String>) immutableList))
        .isSameInstanceAs(immutableList);
  }

  public void testFrequency_multiset() {
    Multiset<String> multiset = ImmutableMultiset.of("a", "b", "a", "c", "b", "a");
    assertEquals(3, frequency(multiset, "a"));
    assertEquals(2, frequency(multiset, "b"));
    assertEquals(1, frequency(multiset, "c"));