* }</pre>
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the discussion in the {@link #addListener} documentation. All its warnings about heavyweight
   * listeners are also applicable to heavyweight functions passed to this method.
   *
   * <p>This method is similar to {@link java.util.concurrent.CompletableFuture#exceptionally}. It

 *       under all environments. We could fight this by fully qualifying the annotation, but the
 *       result will be verbose and attention-grabbing.
 *   <li>We need to be careful about how we suppress {@code suite()} methods in {@code common.io}.
 *       The generated suite for {@code FooTest} ends up containing {@code FooTest} itself plus some

@GwtCompatible
@ElementTypesAreNonnullByDefault
final class RelationshipTester<T> {

  static class ItemReporter {
    String reportItem(Item<?> item) {
      return item.toString();
    }
  }

  /**
   * A word about using {@link Equivalence}, which automatically checks for {@code null} and
   * identical inputs: This sounds like it ought to be a problem here, since the goals of this class

  //    Imagine:
  //    guard.lock();
  //    try { /* monitor locked and guard satisfied here */ }
  //    finally { guard.unlock(); }
  // Here are Justin's design notes about this:
  //
  // This idea has come up from time to time, and I think one of my
  // earlier versions of Monitor even did something like this. I ended
  // up strongly favoring the current interface.
  //

      /*
       * If isDone is true during the call to listenInPoolThread,
       * listenInPoolThread doesn't start a thread. Make sure it's false the
       * first time through (and forever after, since no one else cares about
       * it).
       */
      return false;
    }
  }

  private static final class RecordingRunnable implements Runnable {
    final CountDownLatch wasRun = new CountDownLatch(1);

 *       allocating garbage).
 * </ul>
 *
 * <p>Disadvantages compared to {@code int[]}:
 *
 * <ul>
 *   <li>Memory footprint has a fixed overhead (about 24 bytes per instance).
 *   <li><i>Some</i> construction use cases force the data to be copied (though several construction
 *       APIs are offered that don't).

 *       allocating garbage).
 * </ul>
 *
 * <p>Disadvantages compared to {@code double[]}:
 *
 * <ul>
 *   <li>Memory footprint has a fixed overhead (about 24 bytes per instance).
 *   <li><i>Some</i> construction use cases force the data to be copied (though several construction
 *       APIs are offered that don't).

 * general way.
 *
 * <p>A good example of usage of this class is for HTML escaping where the replacement array
 * contains information about the named HTML entities such as {@code &amp;} and {@code &quot;} while
 * {@link #escapeUnsafe} is overridden to handle general escaping of the form {@code &#NNNNN;}.
 *

     * hopefully could avoid implementing Entry or ValueSetLink at all. (But note that that approach
     * requires us to define extra classes -- unfortunate under Android.) *Then* we could consider
     * lying about the fields below on the grounds that we always initialize them just after the
     * constructor -- an example of the kind of lying that our hypothetical bytecode rewriter would

 *       under all environments. We could fight this by fully qualifying the annotation, but the
 *       result will be verbose and attention-grabbing.
 *   <li>We need to be careful about how we suppress {@code suite()} methods in {@code common.io}.
 *       The generated suite for {@code FooTest} ends up containing {@code FooTest} itself plus some