final Object[] elements;
    final int[] counts;

    // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
    SerializedForm(Multiset<? extends Object> multiset) {
      int distinct = multiset.entrySet().size();
      elements = new Object[distinct];
      counts = new int[distinct];
      int i = 0;

    Counter c2 = new Counter(aa);
    Thread t1 = newStartedThread(c1);
    Thread t2 = newStartedThread(c2);
    awaitTermination(t1);
    awaitTermination(t2);
    assertEquals(SIZE * COUNTDOWN, c1.counts + c2.counts);
  }

  /** a deserialized serialized array holds same values */
  public void testSerialization() throws Exception {
    AtomicDoubleArray x = new AtomicDoubleArray(SIZE);

    Counter c2 = new Counter(aa);
    Thread t1 = newStartedThread(c1);
    Thread t2 = newStartedThread(c2);
    awaitTermination(t1);
    awaitTermination(t2);
    assertEquals(SIZE * COUNTDOWN, c1.counts + c2.counts);
  }

  /** a deserialized serialized array holds same values */
  public void testSerialization() throws Exception {
    AtomicDoubleArray x = new AtomicDoubleArray(SIZE);

    final Object[] elements;
    final int[] counts;

    // "extends Object" works around https://github.com/typetools/checker-framework/issues/3013
    SerializedForm(Multiset<? extends Object> multiset) {
      int distinct = multiset.entrySet().size();
      elements = new Object[distinct];
      counts = new int[distinct];
      int i = 0;

    return multiset(ImmutableMap.of(value1, count1, value2, count2));
  }

  private static <T> ImmutableMultiset<T> multiset(Map<T, Integer> counts) {
    ImmutableMultiset.Builder<T> builder = ImmutableMultiset.builder();
    for (Entry<T, Integer> entry : counts.entrySet()) {
      builder.addCopies(entry.getKey(), entry.getValue());
    }
    return builder.build();
  }

  /**
   * Returns a {@code Collector} that accumulates elements into a multiset created via the specified
   * {@code Supplier}, whose elements are the result of applying {@code elementFunction} to the
   * inputs, with counts equal to the result of applying {@code countFunction} to the inputs.
   * Elements are added in encounter order.
   *
   * <p>If the mapped elements contain duplicates (according to {@link Object#equals}), the element

  }

  /**
   * Returns the given {@code template} string with each occurrence of {@code "%s"} replaced with
   * the corresponding argument value from {@code args}; or, if the placeholder and argument counts
   * do not match, returns a best-effort form of that string. Will not throw an exception under
   * normal conditions.
   *
   * <p><b>Note:</b> For most string-formatting needs, use {@link String#format String.format},

import com.google.common.annotations.GwtCompatible;
import java.io.Serializable;
import javax.annotation.CheckForNull;

/**
 * A mutable value of type {@code int}, for multisets to use in tracking counts of values.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
final class Count implements Serializable {
  private int value;

  Count(int value) {
    this.value = value;

   * references to the map or modify it in any way.
   *
   * <p>The returned multiset is serializable if the input map is.
   *
   * @param countMap backing map for storing the elements in the multiset and their counts. It must
   *     be empty.
   * @throws IllegalArgumentException if {@code countMap} is not empty
   * @since 20.0
   */
  public static <E> ConcurrentHashMultiset<E> create(ConcurrentMap<E, AtomicInteger> countMap) {

    } while (System.nanoTime() - deadline < 0);
    throw formatRuntimeException(
        "Latch failed to count down within %d second timeout", timeoutSeconds);
  }

  /**
   * Creates a garbage object that counts down the latch in its finalizer. Sequestered into a
   * separate method to make it somewhat more likely to be unreachable.
   */
  private static void createUnreachableLatchFinalizer(CountDownLatch latch) {