* However, an implementation may also choose to return {@code true} whenever {@code object} is a
   * {@link Predicate} that it considers <i>interchangeable</i> with this one. "Interchangeable"
   * <i>typically</i> means that {@code this.apply(t) == that.apply(t)} for all {@code t} of type
   * {@code T}). Note that a {@code false} result from this method does not imply that the
   * predicates are known <i>not</i> to be interchangeable.
   */

   * doesn't work: Because nullness analyses typically infer the nullness of local variables,
   * there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (Even if supported added {@code @NonNull}, that would not help, since the problem case

   * Generation, described in Knuth's "The Art of Computer Programming", Volume 4, Chapter 7,
   * Section 7.2.1.2. The iteration order follows the lexicographical order. This means that the
   * first permutation will be in ascending order, and the last will be in descending order.
   *
   * <p>Duplicate elements are considered equal. For example, the list [1, 1] will have only one

    assertEquals(Arrays.toString(events), stopwatch.readEventsAndClear());
  }

  /**
   * The stopwatch gathers events and presents them as strings. R0.6 means a delay of 0.6 seconds
   * caused by the (R)ateLimiter U1.0 means the (U)ser caused the stopwatch to sleep for a second.
   */
  static class FakeStopwatch extends SleepingStopwatch {
    long instant = 0L;

     *
     * <p>If the Thread in use is interrupted before or during execution of the tasks in {@link
     * #queue}, the Executor will complete its tasks, and then restore the interruption. This means
     * that once the Thread returns to the Executor that this Executor composes, the interruption
     * will still be present. If the composed Executor is an ExecutorService, it can respond to

        .createTestSuite();
  }

  // Not specifying KNOWN_ORDER for PriorityQueue and PriorityBlockingQueue
  // even though they do have it, because our tests interpret KNOWN_ORDER to
  // also mean that the iterator returns the head element first, which those
  // don't.

  public Test testsForPriorityBlockingQueue() {
    return QueueTestSuiteBuilder.using(
            new TestStringQueueGenerator() {

   * unspecified if this method is called more than once on the same instance.
   */
  HashCode hash();

  /**
   * {@inheritDoc}
   *
   * @deprecated This returns {@link Object#hashCode()}; you almost certainly mean to call {@code
   *     hash().asInt()}.
   */
  @Override
  @Deprecated
  int hashCode();

 *   }
 * }</pre>
 *
 * <p>With method references it is more succinct: {@code comparing(Foo::aString)} for example.
 *
 * <p>Using {@link Comparator} avoids certain types of bugs, for example when you meant to write
 * {@code .compare(a.foo, b.foo)} but you actually wrote {@code .compare(a.foo, a.foo)} or {@code
 * .compare(a.foo, b.bar)}. {@code ComparisonChain} also has a potential performance problem that

import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A series of tests that support asserting that collections cannot be modified, either through
 * direct or indirect means.
 *
 * @author Robert Konigsberg
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class UnmodifiableCollectionTests {

  public static void assertMapEntryIsUnmodifiable(Entry<?, ?> entry) {
    try {

        IllegalArgumentException.class,
        () -> Traverser.forGraph(createDirectedGraph()).breadthFirst('a'));
  }

  /**
   * Checks that the elements of the iterable are calculated on the fly. Concretely, that means that
   * {@link SuccessorsFunction#successors(Object)} can only be called for a subset of all nodes.
   */
  @Test
  public void forGraph_breadthFirstIterable_emptyGraph() {
    assertEqualCharNodes(