/** A collection of elements to retain, along with a description for use in failure messages. */
  private class Target {
    private final Collection<E> toRetain;
    private final String description;

    private Target(Collection<E> toRetain, String description) {
      this.toRetain = toRetain;
      this.description = description;
    }

    @Override
    public String toString() {

  /** A collection of elements to retain, along with a description for use in failure messages. */
  private class Target {
    private final Collection<E> toRetain;
    private final String description;

    private Target(Collection<E> toRetain, String description) {
      this.toRetain = toRetain;
      this.description = description;
    }

    @Override
    public String toString() {

  /**
   * Removes a single key-value pair with the key {@code key} and the value {@code value} from this
   * multimap, if such exists. If multiple key-value pairs in the multimap fit this description,
   * which one is removed is unspecified.
   *
   * @return {@code true} if the multimap changed
   */
  @CanIgnoreReturnValue
  boolean remove(
      @CompatibleWith("K") @CheckForNull Object key,

   * implementation. Experimentally determined.
   */
  private static final int MAX_HASH_BUCKET_LENGTH = 9;

  // See CompactHashMap for a detailed description of how the following fields work. That
  // description talks about `keys`, `values`, and `entries`; here the `keys` and `values` arrays
  // are replaced by a single `elements` array but everything else works similarly.

  /**

   * Often called multiple times (that is, both when the inputs complete and when the output
   * completes).
   *
   * <p>This is similar to our proposed {@code afterCommit} method but not quite the same. See the
   * description of CL 265462958.
   */
  // TODO(user): Write more tests for memory retention.
  @ForOverride
  @OverridingMethodsMustInvokeSuper
  void releaseResources(ReleaseResourcesReason reason) {
    checkNotNull(reason);

    List<?> exp = copyToList(expected);
    List<?> act = copyToList(actual);
    String actString = act.toString();

    // Of course we could take pains to give the complete description of the
    // problem on any failure.

    // Yeah it's n^2.
    for (Object object : exp) {
      if (!act.remove(object)) {
        Assert.fail(
            "did not contain expected element "

      Class<?> cls, List<String> explicitTestNames, String description, Throwable e) {
    String message =
        String.format(
            Locale.ROOT,
            "Error in automated %s of %s\n"
                + "If the class is better tested explicitly, you can add %s() to %sTest",
            description,
            cls,
            explicitTestNames.get(0),
            cls.getName());

  private enum MyOrder {
    FIRST,
    SECOND,
    THIRD;
  }

  private enum OtherOrder {
    FIRST,
    SECOND,
    THIRD;
  }

  // Given a sequence of lock acquisition descriptions
  // (e.g. "LockA -> LockB", "LockB -> LockC", ...)
  // Checks that the exception.getMessage() matches a regex of the form:
  // "LockA -> LockB \b.*\b LockB -> LockC \b.*\b LockC -> LockA"

 *       parallelizing stream operations.
 *   <li>{@code FluentIterable} contains several features not available on {@code Stream}, which are
 *       noted in the method descriptions below.
 *   <li>Streams include primitive-specialized variants such as {@code IntStream}, the use of which
 *       is strongly recommended.
 *   <li>Streams are standard Java, not requiring a third-party dependency.
 * </ul>

      Class<?> cls, List<String> explicitTestNames, String description, Throwable e) {
    String message =
        String.format(
            Locale.ROOT,
            "Error in automated %s of %s\n"
                + "If the class is better tested explicitly, you can add %s() to %sTest",
            description,
            cls,
            explicitTestNames.get(0),
            cls.getName());